- SOLVE 12 CLUES LIKE THIS! - *
Where it all began. Where the torch was first lit.
Where muscles and sinews strain. Where our heros
win acclaim. Where the symbols hold the key.
KRAKIT” consists of 12 clues on a ready-to-run ZX81 or TS1000
cassette tape (16k RAM). The answer to each clue is the name of a
country, a city or town, and a number. If you are the first qualified
entrant to solve all 12 clues and declared the winner, you receive two
tickets to the city of the secret KRAKIT" vault location. When you arrive
at that location, a check for a minimum amount of $20,000.00 (U.S.) will
be presented to you. The amount of the prize money is augmented weekly
TS1000-ZX81
Mail to:
INTERNATIONAL PUBLISHING & SOFTWARE INC
P O ROT BUFFALO, N.Y. 14216
'>€»*
SYNTAX QUARTERLY/SPRING 1983
A PUBLICATION OF
THE HARVARD GROUP
SYNTAX QUARTERLY
Serving The Timex-Sinclair Family of Personal Computers
Spring 1983
Vol. 2, No. 1
Contents
SQ Staff
Publisher
Kirtland H. Olson, P.E.
Editor
Ann L. Zevnik
Assistant Editor
Pamela Petrakos-Wilson
Technical Consultant
Eric K. Olson
Editorial Assistants
Pamela K. Vinal
Karen Brody
Production
CSA Press
Circulation
Susan C. Shippen
Constance Saarinen
Timothy Parker
Financial Manager
Mary Russo
Designer
RDS Designs
Cover Photography
James Rue Design
Syncwars — An Invasion 1 4
The invasion of Computerburg. by Fred Nachbaur
Geography Review— U.S. States Quiz 19
A review of U.S. geography, by Steven Walley
POKEing Directly to the Display File 22
Use less memory, speed up graphics, by Dan Platt
Simultaneous Linear Equations and
Matrix Inversion 24
Solve equations and invert matrices with this
program— a delight for amateur mathematicians,
by R.A. Woodall
ZX/ TS Home Budget 26
Home finances on your personal computer,
by Michael Roberts
Getting Your Head Straight 3 0
Align the heads on your recorder, by John Andrews
Make-It- Yourself Quiz Program 34
Choose your format, tailor questions and answers,
by Dale F. Lipinski
Build Your Own EPROM Programmer
and Centronics Printer Interface—
Part II 38
Build 2 EPROM read boards and a 2-way Centronics compatible
parallel printer port with step-by-step instructions,
by John Oliger
Operation Codes of the 8080, 8085
and Z80 Processors 46
A complete reference to the op-code mnemonics
of 8080, 8085 and Z80 microprocessors,
by D Martin Flarrell
Departments
4
s' BASIC
8
Reviews
54
Reviews
57
ws
61
64
SYNTAX QUARTERLY/SPRING 1983
This Could be Your Chance
for Fame and Fortune
(or at least fame)
Would you like to see your name in programming tip, explain the func-
print? SQ and SYNTAX newsletter tion of the machine or a command, or
are looking for authors. If you have a describe a hardware project. If you
program or article you d like to share present ideas on programming, it
with other ZX/TS owners, send it helps to include short sample routines
a*on9- demonstrating your ideas. If your
Our requirements are simple: all article discusses hardware, please in-
we ask is that your program run with elude sketches, schematics, or even
no bugs and your article present ac- photos to help readers follow along,
curate information. For both programs and articles,
However, here are a few more de- type your submission or print clearly'
tails that enhance your chances of preferably double-spaced. Put your
being published: name, address and day-time phone
PROGRAMS: Any program for a number on the first page. If you want
fun or useful purpose is a candidate us to return your material to you,
for SYNTAX or SQ. We publish include a self-addressed stamped
game, business, educational, utility envelope.
and science/math programs. Please You can submit to either SYNTAX
send programs on cassette, particu- newsletter or SQ magazine. Gener-
larly if they’re long. We print ally, programs and articles in SQ tend
programs directly from a Sinclair to be longer and more involved than
printer to minimize errors. If you send those in SYNTAX because of space
your program on cassette, it will ap- considerations. Which publication
pear exactly as you entered it. A your submission ultimately appears in
hard, or paper, copy helps us figure is up to the editors,
out any problems that may arise . Also What’s in it for you? Aside from the
include as much documentation as fame and glory of appearing in
you can, including a list of variables SYNTAX or SQ, you’ll receive a
used and their functions. Write com- check from us dependent on the
plete instructions for using your length of the published material. We
program so the most inexperienced pay 7 cents for each 6 characters, in¬
user could not mess it up. Sample eluding spaces and punctuation. This
output also helps, especially if your payment buys us the nonexclusive
program generates charts, graphs, or right to use your material. We can use
numerical tables. Make your program it and so can you, so you can sell it
as user-friendly as possible within the again to anyone you like. Programs
limitations of available memory. Indi- receive a token $2 payment each,
cate how much memory your pro- Not enough to retire on, but often
gram requires. And include the Syn- enough to pay for your subscription,
tactic Sum of the program as listed. So dig through your notes and files
For a copy of the Syntactic Sum pro- and send off anything you think may
gram, contact SYNTAX (address help other users use their computers
following). better. Address submissions to:
ARTICLES: Articles can cover vir¬
tually any topic related to ZX/TS Editor
computers and their applications. SYNTAX/SQ
Our readers run the gamut from ex- Rd 2, Box 457
pert to novice, so we are looking for Harvard, MA 01451
articles written at all levels of com- USA
plexity. Your article can present a
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SYNTAX QUARTERLY/SPRING 1983
■>
SHIM
SQ-ups— Winter 82
Getting Information into Your Computer by Jim Conrad
On p. 6, column 2, line 10 of the first example program
should read:
10 LET B= 17
In the table on p. 8, under “Example” the third entry
should read Reserved Words (TO, RUN, TAN).
On p. 9, column 2, line 10 should read:
10 PRINT “first message”
Improved Super Monzxer Game by Robert Calhoon
Line 240 should read:
240 PLOT 23,21
The last word in line 1700 is correctly spelled MONZXER.
We apologize for incorrectly spelling Mr. Calhoon’s
name.
Syntactic Sum with Variables by Donald J. Beck
In the assembly listing on pp. 18-19, all appearances of
the number 16346 should read 16396 and all ap¬
pearances of the number 16347 should read 16397. The
instances occur at addresses:
32720 (mnenonic and comment)
32721 (comment)
32722 (comment)
32723 (comment)
The code at address 32743 should be 229.
Machine Code Programs — Where and How to Load
Them by William Wentz
On page 21, first paragraph under Variables Storage
Area, the last sentence should read: For ease in placing
the MC into the string and locating the USR address, put
the LET statement containing the MC first in the pro¬
gram, so it will be the first variable in storage.
ZX/TS Directory Program by David R. Rowland
The variables in line 1, 2, and 3 should all be dimen¬
sioned to (90,31), not (1,31) to allow all 90 entries. See
reprinted listing following.
Keyboard Conversions by David M. Straub
In Figure 1, p. 27, every key should have two black dots
indicating pins. Those in the upper right corner are miss¬
ing one dot.
Using Extra Keys on Big Keyboard — A Simpler Ap¬
proach by David Ornstein
Please note that the anode of D3 indicated on the
schematic is for a ZX80. On a ZX81 or TS1000, that
diode is D6.
Build Your Own EPROM Programmer and Centronics
Printer Interface by John Oliger
Except when referring to ROM installation inside the
ZX/TS, Dn always means Dn’ (which appears at the
edge connector) in parts I and II of this article. Dn means
data line n.
Program Clarification
Parts of programs in SQ Winter 82 did not print as clearly
as we would like. Here are portions of those listings
reprinted for easier reading.
A Program to Index Articles
1© DIM
20 DIM B$(400,24)
30 DIM C$C400, 5)
30 PRINT RT 3,3; “5YNTRX INDEX*1
12© PRINT RT 9 , 1©; " 1 . RPPEND"
13© PRINT RT 10,10; '*2. LIST"
14-© PRU5E 50000
15© POKE 154-37,255
150 IF INKE*y$ = "l" OR INKEY$="A"
THEN GOTO 1000
220 INPUT K
230 IF K < 1 OR K >6 THEN GOTO 220
2 2© GOTO K *5© +25©
250 SCROLL
250 PRINT ** «";C$(I);,,-";B$(I)
255 SCROLL
27© PRINT " “UOL / ISSUE / PRGE ";R
; "/“i 5; C
272 SCROLL
275 PROSE 90
230 IF INKEY$="P" THEN PRUSE 50
000
235 POKE 154-37,255
29© RETURN
30© FOR 1 = 1 TO 4-00
305 LET R=INT C (CODE R$(I) -1) /I
2)
31© LET B=CQDE R$<I*-R*I2
315 LET C=CODE R$ l 1+4-00)
32© GO-SUB 250
325 NEXT I
Improved Super Monzxer
The words in reverse video are:
2030 HURRAY HURRAY
14-20 PRINT "THERE IS R SPIDER IN
YOUR ROOM AND HE IS HUNGRY"
14-23 PRINT RT 9.10; " K
14-24- PRINT RT
1©,9; "i
14-25 PRINT RT 11,9; "1
14-27 PRINT RT I2,I7;"IL IL IL"
14-28 PRINT RT 1 4-, 7; "YUM YUM ERTE
M UP"
14-29 PRUSE 100
14-3© FOR 1=1 TO 10
14-4-0 IF YR=P(I) THEN GOTO 14-70
14-5© NEXT I
14-50 GOTO 154-0
14-70 IF YL=5 THEN GOTO 1520
Continued Next Page
4
SYNTAX QUARTERLY/SPRING 1983
148© CLS
1490 PRINT "T5K, T SK , YOU PELL I
15©0 LET YR=YR+20
X505 XP YL>=2 THEN GOTO 154-0
303©
304-0
3050
3G6G
3070
SET 3 *
3030
3000
3100
3110
3120
3130
314-0
315©
3160
3165
3170
350©
3510
3520
3530
■/"
3S4-©
354-2
354-4-
354-6
3550
3560
LET K$=INKEY$
XP K$="Y" THEN GOTO 3070
IP K$="N" THEN GOTO 313©
GOTO 3020
PRINT RT 10,6; “SAME TUNNEL
PAUSE 900
LET K$=INKEY$
XP K$="Y" THEN GOTO 525
IP K$="N" THEN GOTO 300
GOTO 3060
CLS
PRINT RT 10,20; "HAR HRR"
PRINT RT 12,18; "YOU LOSE"
LET END=1
FAST
GOTO 70
PRINT RT 10,9; "TT TT TT"
print rt 11,8; " tHHIHHHHHMHI
r
print rt 12,5; ■■ > >= = =BBHHHi
Print rt TSSM
print rt 14- , 12;
PRINT RT 0,20; *‘7
PRINT RT 7,24;"?"
PRINT RT 5,27;"?"
PRINT RT 16,22; "YA GOT HE"
RETURN
10 REM ®_N 7?E« RND GOSUB ???»T
GuSUB ??RND GOSUB 7 POR ; GOSUB
§ GOSUB ??RNDEi RND GOSUB PI6, RN
DE "RND GOSUB PIS “RND GOSUB ?T GC
SUB PI RRND TRN
2© LET H$ = "
4-0 LET L =LEN H$^3
5© LET M=L
6© IP L <20 THEN LET M=20
70 POKE 16507, M
8© PRINT USR 16514-;" BYTES SAU
EL>"
O0 LET N=PEEK 16388 +256 +PEEK 1
6380
100 PRINT "RECORD USR RDDRESS "
' lie POR X =3 TO L*3 STEP 3
120 POKE N,16*CQDE H$(X-2)+CODE
H$ ( X - 1) -4-76
130 LET N=N + 1
140 NEXT X
150 PRINT " HRCHINE CODE LORDED
SYNTACTIC SUH:
£304-4- , 8K ROM
ZX/TS Director y Program
The words in reverse video are:
62 EVER AGAIN
196 MEMORY FULL
197 CONT
455 NONE FOUND
457 CONT
490 CONT
915 the Y in DIRECTORY
MC Programs — Where and How to Load Them
10 REM
20 LET
40 LET
5© LET
6307-2
6© POR
7© POKE
80 POKE
15
O0 RRND
100 POKE
CODE H$( I
110 NEXT
120 POKE
130 POKE
20© REM
SYNTACTIC
12EI.RNDLN I^TAN
N=LEN "h$/3
D=PEEK 16306 +256 fPEEK 1
1=1 TO N
16515 , INT C (D + I) /256 3
lt>514 , D + 1—256 fPEEK 165
USR 16516
D + I , 16fCODE H$ * 1*3-2 > +
*3-1) -476
I
D — 1 , INT C (N+2) /256)
D -2 , N +2-256 +PEEK ( D - 1 )
SUM: 20307, SK ROM
10 REM
2© LET
40 LET
5© LET
6307-2
60 POR
70 POKE
80 POKE
15
O© RRND
100 POKE
4-1)
110 NEXT
12© POKE
130 POKE
200 REH
SYNTACTIC
12El^NDLN SafcTRN
D$="
N=LEN D$/3
D=PEEK 16306 +256 +PEEK 1
1=1 TO N
16515, INT ( (D + I) /256 )
16514 ,D+I— 256+PEEK 165
USR 16516
D+I, URL D$ (1*4-3 TO I*
D-l , INT C (N+2) /256 )
D -2 , N +2 -256 *PEEK ( D - 1 )
SUM: 10287, SK ROM
1 DIM N$ (00.31)
2 DIM S$(90,31)
3 DIM T$(90,31)
6 REM STRRT PROGRRM WITH "GO
TO 16 " AFTER INITIAL RUN
O LET D=0
10 PRINT RT 0, 12; "HELLO" ; RT 2,
l; "ENTER CODE POR UHAT IS WANTED
11 PRINT RT 4,0; "1. ENTER MOR
E NAMES”
12 PRINT "2- CHRNGE SELECTED
NRME OR OTHER DATR"
^13 PRINT "3. CHECK RLL ENTRIE
14 PRINT "4. LIST RLL NAMES B
EGINNING"," WITH R LETTER"
^ if PRINT "5. LIST RLL NRMES I
N STATE "
16 PRINT "6. LIST RLL NRMES N
OT IN STATE" /
17 PRINT "7. LIST RLL NRMES &
Y ZIP CODE"
18 PRINT "8. LIST RLL CODED N
AMES"
IO PRINT "O. SRUE REUISED DIR
ECTORY"
16© INPUT U$
165 CLS
170 IP U$="Y" THEN GOSUB 75©
X^S^PRINT RT ©,©; L, ,N$ (L) ,S$ (L)
175 PRINT "RLL CORRECT? Y OR N
* 178 INPUT U$
180 IP U$<>"N" THEN GOTO 184
181 LET R=1
182 GOSUB 330
183 LET R=©
Continued Next Page
SYNTAX QUARTERLY/SPRING 1983
134- Cl_S
135 PRINT RT 6,0; "ANY MORE NRME
ST V OR N . "
187 INPUT U$
100 CI_S
102 XF U$<>"Y" THEN RETURN
105 NEXT L.
34-0 INPUT Q
350 XF Q=1 THEN INPUT N$(L)
355 XF 0=2 THEN INPUT S$CL, TO
10)
360 XF 0=3 THEN INPUT T$ CL , TO
10)
365 XF 0=4- THEN INPUT T$(L.23 T
O 25)
378 XF 0=5 THEN INPUT T$iL.27 T
O 31)
375 XF 0=6 THEN INPUT S$U_.2© T
O )
330 IF 0=7 THEN GOSUB 750
335 IF 0=3 THEN GOTO 35
333 IF 0=0 THEN GOSUB 660
330 CL5
305 GOTO 305
4-00 PRINT RT 4-,©; -'ENTER LETTER f
S) OR NRME TO BE” ."LOCRTED"
4-©5 LET 0=0
4- 10 INPUT
4-20 CLS
4-3© FOR L = 1 TO D
4-4-© IF U$=N$CL, TO LEN U$) THEN
GOSUB 4-65
4-50 NEXT L
4-55 IF 0=0 THEN PRINT RT 7.10; "
4-57 PRINT RT 20.8; "PRESS "
TO REGRIN MENU-
4-60 STOP
4-62 RETURN
4-65 PRINT L, ,N$(L) ,S$CL) ,T$(L) ,
' 478 LET 0=0+1
4-30 IF INT C0/4-) =0/4- THEN GOTO
4-9©
4-85 RETURN
4-0© PRINT RT 20,0; -PRESS -
-- TO RESUME LISTING"
4-02 STOP
4-05 RETURN
4-07 GOTO 4-5©
50© PRINT RT 5,©; "ENTER TUO LET
TER STRTE CODE-
505 LET 0=0
51© INPUT U$
515 CLS
52© FOR L = 1 TO D
525 IF U $ =T $ CL . 23 TO 24-) THEN G
OSUB 465
530 NEXT L
54-0 GOSUB 4-55
55© RETURN
6©0 PRINT RT 5,0; "ENTER TUO LET
TER STRTE CODE-
605 LET 0=0
610 INPUT U$
615 CLS
620 FOR L =1 TO D
625 IF U$oT$(L,23 TO 24-) THEN
GOSUB 4-65
630 NEXT L
64-0 GOSUB 4-55
65© RETURN
66© LET N$(L) =N$(D)
665 LET S$CL)=55MD}
67© LET T$CL) =T$CD)
675 LET N$ CD) = " "
660 LET 54(D) =” "
685 LET TiCD)=" "
60© LET D =D — I
605 RETURN
70S PRINT RT 5.6; "ENTER 5 NUMBE
R ZIP”
S INWARE provides high-quality
machine-code programs for the
TS1000 or ZX81.
HOT Z
HOT Z is the machine-programming
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labels let you understand other pro¬
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Z EXTRA is a display creator/con¬
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or display multiple screens of text and
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eight plot directions, 4x4 and 8x8 char¬
acter sizes, and much more.
Z EXTRA'S displays provide horizontal
or vertical scrolls of multiple screens
against a background screen, or timed
page flips for simple animation. Screens
can be transferred to BASIC strings to
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Z EXTRA requries a ZX81 or TS 1000
with at least 16K of RAM and is espec¬
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BOX 323, DIXON, NM 87527
6
SYNTAX QUARTERLY/SPRING 1983
l
I
I
BEHIND EVERY
GOOD SINCLAIR
IS A MEMOPAK
If you own a Timex-Sinclair 1000 or
ZX81 computer, you should have a
Memopak behind it. From increased
memory to high resolution graphics,
Memotech has a Memopak to boost your
system’s capabilities. Every Memopak
peripheral comes in a black anodised
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you to continue to add on and still keep an
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High Resolution Graphics
Order at no risk
All Memotech products carry our 10
day money back guarantee. If you’re not
completely satisfied, return it in ten days
and we will give you a full refund.
And every Memotech product comes with a
six month warranty. Should anything be
defective with your Memopak, return it to
us and we will repair or replace it free of
charge. Dealer inquiries welcome. To order
any Memotech product call our toll-free
number 800/662-0949 or use the order
coupon.
CORPORATION
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(303) 986-1516
TWX 910-320-2917
1 64K RAM
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j 32K RAM
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Memopak 64K RAM The 64K RAM extends the
memory of your Sinclair by 56K to a full 64K. It
is directly addressable, user transparent, is
neither switched nor paged and accepts such
BASIC commands as 10 DIM A (9000). The
Memopak 64K turns your Sinclair into a
powerful computer suitable for business,
recreational and educational use. No additional
power supply is required.
Memopak 32K RAM The 32K RAM Memopak
offers your Sinclair a full 32K of directly
addressable RAM. Like the 64K Memopak, it is
neither switched nor paged and enables you to
execute sophisticated programs and store large
data bases. It is also fully compatible with
Sinclair’s or Memotech’s l6K RAM to give you a
lull 48K of RAM.
Memopak 16K RAM The Memopak 16K RAM
provides an economical way to increase the
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Memopak 16K or Memopak 32K tp give 32K or
48K of RAM respectively.
Memopak High Resolution Graphics The
Memopak HRG contains a 2K EPROM monitor
and is fully programmable for high resolution
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Memopak Printer Interface The Memopak
Centronics Parallel or RS232 Interface
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beginners* basic
Exploring String Functions
by James A. Conrad, Seattle, WA
Most novice programmers don’t understand much about
string functions. And many not-so-novice programmers
don’t use them to their full potential. Functions seemed
relatively unimportant when they started learning
BASIC — something to “get to later.” Well, “later” is now.
String functions are easy to understand.
String functions are especially useful in writing input¬
checking and output-formatting routines — areas where
many programs are weak. A few hours invested in studying
string functions will pay dividends in user-friendly programs.
Many programmers tend to confuse functions and
statements. A statement is an instruction to the com¬
puter, telling it to do something. It contains (or is) a verb,
such as PRINT or GOTO. Most functions calculate or
convert. They’re like self-contained subroutines; SQR x,
for example, computes the square root of x.
The major BASIC functions perform arithmetic or string
operations. String functions analyze and manipulate
strings. (For a refresher on strings, see SQ Winter
1982. — Ed.) They’re indispensable in input-checking and
output-formatting routines.
A Few Words about Functions
Functions have two parts: a title and an argument. The title
describes, in BASIC, what the function does, for example,
LENgth, VALue. The argument follows the title and
serves as the input to the function. The function uses this
input and returns a result. A function’s argument is pro¬
nounced “of”— to read the function LEN A$, for exam¬
ple, you say, “length of A string.”
You can do almost anything with a function that you
can with a variable. You can print it. If it’s numeric, you
can add or subtract it. You can even put it in the argu¬
ment of another function, for example, LEN A$(2 TO 5) .
(This is called nesting. When you nest functions, be sure
you put a right parenthesis for every left one.) About the
only thing you can’t do with most functions that you can
do with variables is assign values to them with assignment
statements (see SQ, Winter 1982).
The String Functions
First, a few definitions relating to string functions:
String: a set of alphanumeric and/or graphic characters.
String variable: name given to the memory cell(s) to
which the string is assigned. Your ZX/TS gives you 26
string variables, A$ through Z$.
Substring: portion of a string consisting of consecutive
characters.
Expression: a constant (such as 12 or “BOB”), a
variable (X, Y$), or a formula (7*Y, K$ + “DAVE”). If a
formula is used in the argument of a function, you must
put it in parentheses.
Here’s a summary of string functions, what they do,
and a program line that prints an example. The symbols I
use in the arguments are:
$: string being analyzed
sub$: substring
len: length of string or
substring
pos: position in string
x: any numeric expression
or number the com¬
puter can handle
chr: character (in quotation
marks) or character
code
cod: character code (0-255)
Any of these except chr can be a constant, variable or
formula.
We’ll set up line 10 to make a nine-character string A$
to play with. Enter line 10 on your computer:
10 LET
Slicing
Slicing is a process that gets substrings from strings. For
the academically inclined, slicing is a function without a
title— the entire slicing notation is the argument. The gen¬
eral form of the slicing notation is:
string expression ( slicer )
The slicer must be enclosed in parentheses. Its general
form is:
( position 1 TO position 2)
It also has several abbreviated forms, shown following:
Here is the full form for slicing. It returns a substring of
string $, beginning with character number posl and
ending with the character in pos2:
$(posl TO pos2)
Enter line 20 and RUN our two-line program. (Note
that you don’t need to type in the spaces around TO.
Your ZX/TS does that automatically when you use
SHIFT 4 to enter TO).
20 PRINT "CHRRRCTER5 2. 3, RND
4- OP R$ RRE: ";R$C2 TO 40
You’ll see 234 on your screen.
Now some shorthand notations:
$( TO pos2) posl omitted returns the left portion of
string $ through pos2.
Add line 30:
8
SYNTAX QUARTERLY/SPRING 1983
BEGINNERS1 BASIC
3® PRINT "THE FIRST 4- CHHRflCTE
RS OF R$ RRE : ";Rt( TO 4-J
This prints 1234.
$(posl TO ) pos2 omitted returns the right portion of
string $ from posl through the final character. Add line
40 to our example program:
PRINT -the right side of r*
j FROM LHflRSCTER 5 IS: ";R$(5 TO*
Line 40 will print 56789.
$(pos n ) or $(pos n TO pos n) gives you the character at
pos n in string $. Try line 50:
SO PRTNT "the 4-TH CHRRRCTER OF
R * IP : ; R $ C 4- J
$() or ${ TO ) gives you the entire string $ as a substring.
Line 60 demonstrates:
60 PRINT "R* IS: ";R$f>
It prints 123456789.
LEN $ returns the number of characters in string $. Try
line 70, remembering that LEN is a function (press
SHIFT ENTER, then the K key):
IN®fl*RXsT ::?hENER*OF CHflRflCTERS
You’ll get 9.
VAL $ determines the numeric value of string $. Line 80
shows this (VAL is a function on the J key):
";Ufi(_Pfl*NT “THE VRLUE OF R* IS:
We get 123456790. Note the computer rounded our
nine-digit number to eight significant digits.
STR$ X converts a numeric expression X into a string.
Try lines 90 and 100 (STR$ is a function on the Y key):
30 LET R=333
..f?® PRINT "THE STRING OF R IS:
_« O t n 5 ft
This prints 333.
CODE $ returns the character code number of the first
character of string $. You’ll get zero if string $ is a null, or
empty, string or if the first character is a blank space
(character code 0). Line 110 demonstrates (CODE is a
function on the I key):
II® RRINI "8$ BEGINS WITH CHRRR
LTER CODE NUMBER: CODE R$
Line 110 prints 29— the character code for 1 (check your
manual). Try just entering PRINT CODE “1”. You’ll also
get 29.
CHR$ cod gives you the character, in a one-character
string, corresponding to the character code cod. Remem¬
ber, cod can be an expression (constant, variable or for¬
mula) whose value falls between 0 and 255. CHR$ is a
function on the U key. Enter line 120:
DE2f9 P?|NT- "CTER ™ CO
This prints 1.
Workhorse
Slicing is the workhorse of string manipulation. Run this
quick FOR-NEXT loop for a display of its operation:
18 LJET B$='*RBCDE;"
28 FOR X-X TO 4>
38 PRINT TO XI
4-8 NEXT X
We see that as X increases, the printed string changes:
when X is the screen shows
1 A
2 AB
3 ABC
4 ABCD
This is the equivalent of LEFTS (B$,X) in common
BASICs. Sinclair BASIC does not have this function.
Now change line 30 to:
30 PRINT B $ (X TO )
Remember not to type in the spaces around TO — use
SHIFT 4. RUN our program. Now we get:
when X is the screen shows
1 ABODE
2 BODE
3 CDE
4 DE
This is equivalent to the MID$(B$,X) function found in
other BASICs.
Try another change:
30 PRINT (X TO X+l)
Now we see:
when X is the screen shows
1 AB
2 BC
3 CD
4 DE
This works like MID$(B$,X,2) in other BASICs.
Here’s a tricky one. Change line 30 to read:
3© PRINT B$iLEN B*-X TO }
This produces:
when X is
1
2
3
4
the screen shows
DE
CDE
BCDE
ABCDE
This is the equivalent of RIGHTS (B$,X) in common
BASICs.
SYNTAX QUARTERLY/SPRING 1983
<■
BEGINNERS’ BASIC
Here’s a quick program that gets the same result (input
STEF using SHIFT E):
10 LET B$ = ,*fiBCDE'*
20 FOR X=4- TO 1 STEP -1
30 PRINT CX TO )
4-3 NEXT X
If you can visualize how and why these last two pro¬
grams produce the same result, you have a good under¬
standing of slicing.
Concatenation
Concatenation (pronounced kon-kat-e-NAY-shun) is a
fancy word that means a combination, joining, linking, or
chaining. We can concatenate, or link, strings by using
the concatenation operator, the plus ( + ) sign. When it
works on strings, it joins them. It doesn’t perform
arithmetic addition.
We can concatenate strings from string variables or
characters enclosed in quotation marks. To see how this
works, RUN this demo program:
13 LET F$=MDIftNft"
20 LET L$=“ JONES"
30 LET N$=L$+", **+F$
4-0 PRINT N $
Line 30 concatenates “JONES” in variable L$, a string in
quotation marks consisting of a comma and a space, and
“DIANA” in variable F$. It assigns the manufactured
string to variable N$. Line 40 prints it: JONES, DIANA
What’s in a Name?
Let’s assume we have a name stored in variable N$, in a
mailing list, for example. (In an actual program, we
would probably have a series of names stored in an
array.) We want to separate the first and last names into
the variables F$ (first name) and L$ (last name).
Here’s a routine to get the first name (remember, the
computer ignores REM statements when executing a
program):
10 LET N$=“flNN DOYLE"
10© REH ROUTINE TO GET F$
113 FOR X = 1 TO LEN N$
120 IF N$(X>=" " THEN GOTO 14-0
130 NEXT X
14-0 LET F$=N$C TO X-i)
150 PRINT F$
How does it work? Lines 110 and 130 set up a FOR-
NEXT loop that sequentially examines each character of
N$. Line 120 is the “do” portion of the loop. It uses the
slicing function to test each character one at a time for a
space (“ ”) in N$. When the space is found we have the
first name.
Let’s step through the loop and see what happens. On
the first pass the index variable (counter), X, equals 1.
The IF portion of line 120 looks at the first character,
N$(l), which is “A.” It’s not a space, so X is set to 2 for
the second pass. The second character, N, is tested. On
the fourth pass X = 4 and the slicing function finds the
space it’s looking for. Because the fourth (Xth) character
is the space, we know that the first name is X-l characters
long. The THEN portion executes and jumps to line 140.
Line 140 assigns the left X-l (three) characters of N$,
which are ANN, to variable F$.
Now let’s find the last name. We’ll use a different
technique:
2@0 REH ROUTINE TO GET L$
210 FOR X=LEN N$ TO 1 STEP -X
220 IF N$TX> =" “ THEN GOTO 24-0
230 NEXT X
24-3 LET L $ =N$ iX + X TO I«
250 PRINT L$
Here we step backwards from the right side of N$, testing
for a space. When the computer finds it, the THEN por¬
tion of line 220 executes and transfers program control to
line 240. The slicer in line 240, (X-l- 1 TO ), deletes the
left X characters from N$ and returns the right side from
character X+ 1 to the end of the string. The LET state¬
ment assigns the right side of N$ to variable L$.
Dimensioning Strings
Strings and string variables have size, or length. Regular
string variables are the size of the alphanumeric informa¬
tion they contain. We can, however, set them to a fixed
size, using a DIMension statement.
DIM statements define the number of characters in the
string variable and initially fill it with that number of
spaces (DIM is also used to DIMension arrays— a subject
beyond our scope here). The statement DIM A$(6), for
example, creates a string of 6 spaces in variable A$.
A$ will remain 6 characters long no matter how many
or how few characters we try to assign it. You can
redimension a dimensioned string to a new size. But if
you do, the computer will reinitialize it with spaces and
erase its previous contents. Once dimensioned, a string
cannot be undimensioned.
Chopping and Padding
What earthly good is a fixed-size string variable?
Suppose we have a field, or space, 16 characters wide
for a name. We want to change our string so it has exactly
16 characters. How do we do it? Let’s try it first with a
long name, then with a short one:
10 LET N$="KORZENIOU5KI , STRNI
5LOU"
1@ LET N$="DOE, JfiNE"
Note that Stan’s name has 23 characters and Jane’s has 9.
We’ll assign the result to variable X$. It’s easy— we’ll
just use the DIM statement to create a predefined string
variable of 16 characters:
100 REM ROUTINE TO MRKE R 16-CH
RRRCTER STRING
110 DIM X*( 15)
120 LET X$5=N$
10
SYNTAX QUARTERLY/SPRING 1983
BEGINNERS1 BASIC
Now we’ll print the string from line 130, concatenating a
period to show where the string ends. We’ll print its
length from line 140:
13© PRINT + " "
14-© PRINT "LENGTH OP >;$ IS ";LE
N X$
Line 110 DIMensioned X$ to 16 characters. When line
120 assigned N$ into this 16-character X$, Stan was
chopped down to size— the computer chopped off the
last seven characters of his name (the fancy word is “trun¬
cated ). When we assigned Jane’s 9-character name to
the dimensioned variable, the computer added seven
spaces to it (this is called padding).
Even if the previous contents of the dimensioned string
were non-blank characters, as in Stan’s case, assigning a
shorter string, like Jane’s name, erases the previous
characters and pads the remainder of the string with
spaces.
Experiment
Here’s one to try on your own. Give Jane and Stan mid¬
dle names. Put their first names first in N$ (for example,
“Jane Carol Doe”). Now write a routine that puts each
name in a 20-character field using this format: last name,
comma, first initial, period, space, middle initial, period!
For Jane’s name, the result should be: Doe, J. C. fol¬
lowed by 10 spaces.
Removing Trailing Spaces
When printing a string from a dimensioned string
variable, you will often want to remove trailing spaces.
(Have you ever received a computer- written letter that
starts, Dear Ms. Doe , You have just won. . .”?)
Here’s a routine to get rid of those ugly spaces (use
SHIFT T for the not-equal sign in iine 120):
10 DIM T$(I6)
11 "!NPUT « T«r string-
4-0 PRINT T* + "."
TMn0cS^?OUTINE TO REHOUE TRAIL
JLNb OrRCEo
110 FOR X=LEN T$ TO 1 STEP -1
111 ■’ THEN GOTO ***
1^© LET ft$=T*M TO X)
150 PR INT ft $ + " « “
160 GOTO 20
The routine loops backward through T$ with line 120
testing each character for a space. When it finds a non¬
space character (that is, the expression T$(X)< > “ ” is
true), the program goes to line 140. Here the string ex¬
cluding the trailing spaces (that is, T$( TO X)) is assigned
to A$. Lines 40 and 150 print the test string before and
after removing the trailing spaces, concatenating a period
on the end to show the length of the string.
Programming Tips
1 . Function titles appear under most letter keys. Pressing
the SHIFT and FUNCTION/ENTER keys will print a
reverse video F (function) cursor on the message line.
This allows you to type the function title as you would a
statement.
2. Parentheses around a function’s argument are op¬
tional unless the argument is a formula.
3. Functions, including slicing, have the last priority (12)
in the computer’s order of operations. You’ll have to
define concatenated string expressions by putting paren¬
theses around them before slicing them. For example, you
have to program the expression A$ + “,” + B$ as
(A$ 4- “,” + B$) (sheer) to avoid slicing only B$.
4. Use the single character slicer in input-checking
routines to allow a yes/no input of either the first letter or
the entire word. In the following example, YES goes back
to the program start and NO stops. You can change these
to suit your needs.
IS© PRINT "ANSWER YES OR NO"
130 INPUT R*
14-0 IF R$<1)="Y" THEN GOTO 1©
15© IF R$C1)="N" THEN STOP
5. A string variable, once dimensioned, can’t be un¬
dimensioned. But it can be redimensioned— and its con¬
tents reset to spaces. Previously dimensioned string
variables are practically useless as regular variables. If you
use dimensioned string variables more than once in a
program (for chopping and padding, for example), see if
you can redimension and recycle one you used before.
You have a limited supply (26) of string variables, so
unless you recycle, it’s easy in a complex program to run
out of them.
6. The VAL function must be the first item in an
arithmetic formula. If you can’t rewrite the formula to put
VAL at the beginning, assign the VAL function to an
arithmetic variable first. Then use the variable in the
formula.
VAL, if used in a PRINT AT, PLOT or UNPLOT state¬
ment, must be the first (row) coordinate. To use it as the
second (column) coordinate, assign it first to a variable.
For example, change this line:
. t
14-0 PRINT ftT 12 , UftL "C"
to these lines:
135 LET C=UftL "C"
14.0 PRINT ftT 12..C
7. Your manual’s appendix shows the complete Timex
Sinclair character set. Here’s a little program that lists
them all:
10 REH PRINT CHARACTER SET
20 PRINT "CODE" , " CHARACTERS
30 FOR X=© TO 255
4-0 PRINT X , CHR$ X
50 NEXT X
Codes 67-111 and 122-127 will show as a “?’
character. These codes aren’t used for characters.
SYNTAX QUARTERLY/SPRING 1983
iUnfCgl BEGINNERS* BASIC
TRANSLATION TABLE
String Functions
No “standard” BASIC language exists — only dialects. This table summarizes the main differences between most
common microcomputer BASIC dialects and Sinclair BASIC (used in ZX81s and Timex Sinclair 1000s). The table
refers only to statements and operations used in or related to the accompanying article. It should help you translate
programs written in common dialects into Sinclair BASIC. The accompanying article defines the italicized symbols.
How to Use It
What It Does
in Common
Sinclair
Example
or Is
BASIC
BASIC Translation
LEFTS
Returns the left len
Most dialects use.
Not available. $( TO len)
($,len)
characters of string $.
MID$
Returns a sub¬
Most dialects use.
Not available $(pos TO pos + len)
($, pos, len)
string of string $,
beginning with
character number pos
and having length of
len characters.
M1D$
Returns the entire sub¬
Most dialects use.
Not available $(pos TO )
($, pos)
string right of position
(len omitted)
pos.
RIGHTS
Returns the right len
Most dialects use.
Not available. $(LEN $ - len TO )
($, len)
character of
string $.
ASC($)
Returns ASCII* code
Most use common
Has own Use CODE $
number of the first
code for punctua¬
codes, unre¬
character of string $.
tion, numbers,
lated to ASCII.
and uppercase
No cursor
(* American Standard
letters but differ
control codes.
Code for Information
for graphics
Interchange)
characters and
cursor control
codes.
DIM $(x)
Dimensions string
A few dialects
Optional to No changes needed.
variable $ to x charac¬
require dimen¬
predefine string Use to simplify chop-
ters and fills with
sioning of strings,
size. ping and padding
spaces.
most don’t allow.
routines.
Redimensioning
Redimensions string
Most dialects don’t
No restriction. No changes needed.
variables (as above).
allow.
See Tip 5 for use.
Parentheses
Enclose function’s
Most dialects
Optional on Can usually be
argument.
require.
most functions. omitted. Best to in-
Slicers require elude (for
(Tip 2). portability).
12
SYNTAX QUARTERLY/SPRING 1983
1
2
t
S
§
a
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2
I
8
*
8
II
s
2
8
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Is
1
2
a
1
2
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Get serious about ZX81
& 15 WOO Computing
Cassette Software
IX FORTH
A complete implementation of the FORTH language for
the ZX81 and TS1000 computer.
FORTH's most distinctive feature is its flexibility. The
basic unit is the word — the programmer uses existing
words to define his own which can then be used in fur¬
ther definitions. FORTH is a compiled language so pro¬
grams run very fast (typically five times faster than
BASIC).
ZX-FORTH is supplied on cassette and is accompanied
by extensive documentation:
56-page Users Manual
8'Page Ed^r Manual Z43 $29.95
ZXBUO
Machine Code Monitor and Disassembler
ZXBUG is a powerful tool for machine language pro¬
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to the top memory. ZX BUG works in hexadecimal
(base 16), not decimal, so ail addresses are a max¬
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mands.
Z41 $14.95
CA. Assembler
This Machine Code program occupies 7K of memory
and locates itself at the top of memory. The program is a
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The monitor has facilities to inspect memory, registers
and run machine code programs
Z40 $14.95
TOOLKIT 9 Powerful New Functions!
RENUMBER. This routine renumbers a program in any
step and from any line up to 9999
DELETE. This command deletes a group of lines in a pro¬
gram.
MEMORY. Prints how much spare memory is available.
DUMP. Displays current values of string and numerical
values, except arrays.
FIND. Will find any string of up to 255 characters and list
each line containing that string.
REPLACE. Replaces any string of up to 255 characters
by any other string.
SAVE. Transfers program in computer to below RAM-
TOP.
APPEND. Allows two programs to be joined.
REMKILL. Removes all REM statements from a program,
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Z42 $14.95
z-aid i a
Includes the following routines:
VERIFY confirms whether a program has been recorded
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Mload/Msave enables a specified block of memory to be
saved. VPTR can be used within a BASIC program to
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CHAIN allows the second part of a BASIC program to be
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Z AID 1.0 is convenient to use, being loaded from tape,
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★ Allows you to LOAD and SAVE ZX81
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★ LOADER occupies less than 500 bytes (V2 K) of
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KEYBOARD MONITOR is a user-friendly
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user-friendly portion of the program can be
removed for direct access to Machine Code
Monitor. Both parts reside at RAMTOP and are
user transparent. Full details are given in the
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FAST LOADER also resides above RAMTOP
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Reliability and compatability: Fast-Load is an
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A full-sized professional keyboard for the ZX81 Features
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Equivalent in performance to Times Sinclair RAM.
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Expands the capacity of the T/S 1000 or ZX81 to its
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Coming soon: 32K RAM PIGGY BACK
Can be used as a stand-along memory, or in conjunc¬
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MEMORIES
CRAMIC-81 16K CMOS RAM
NEW RAM PACK STORES 16K EVEN WITH POWER
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CRAMIC-81 is a 16K RAM pack using CMOS
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SYNTAX QUARTERLY/SPRING 1983
=n SOFTWARE— GAME
r==Tl
^ v by Fred Nachbaur, Syncware, El Monte, CA
8K ROM/1 -16K RAM
SYNC WARS -
An Invasion
This game will help you improve your speed and accu¬
racy with the ZX/TS keyboard while providing
recreation .
Computerburg is being invaded by a squad of ten
dread Synclons, who beam in, one at a time, from the
hyperspace deep within your computer. Your job is to
zap them as they appear on your screen. However, being
clever little invaders, they each bring along a Syncloid In¬
visibility Robot (S.I.R.) which emits a field that hides the
Synclon from view. Both the Synclon and the S.I.R. may
appear anywhere on your viewscreen, but never in the
same place.
At your disposal you have powerful lasers (the 38 keys
on your keyboard, except SHIFT and SPACE/BREAK).
By firing a laser corresponding to an invader’s position
you can destroy both types of invaders.
Press any key to start the invasion. The first Syncloid
Invisibility Robot appears, surrounded by his field. You
must destroy the robot to deactivate the field, thus making
the Synclon invader visible. Next, you must zap the
Synclon to score. If you miss the S.I.R., the field disturb¬
ance is enough to tingle the Synclon’s aerials, giving
away his position. If you’re fast, and push the right laser
in time (V3 second) you can still hit the Synclon and
score. Also, if you’ve destroyed the robot but miss the
Synclon, you have a brief amount of time to correct your
error and shoot again. Your shot is even valid if you miss
the S.I.R. entirely but happen to hit the Synclon.
Destroying the robot slows the alien’s transporter
enough to give you about one and a half seconds to
shoot the invaders, but this time decreases as subsequent
Synclons beam in. To get the tenth team, you have only
one second to hit the S.I.R. and then the Synclon. If you
miss, or exceed the time limit, the Synclon vanishes again
into your computer, to cause strange crashes and other
nasty deeds. (Not really, but buy the premise and you’ll
enjoy the game more.)
To enter the program into a TS1000 (with 2K RAM)
without RAM pack, see the instructions. The program will
not fit into IK ZX81s, but will run with an external RAM
pack. If you are using an external RAM, see the 16K
14
modifications. You can simulate a 2K machine with your
16K ZX81 using POKE 16389,72, then NEW. The rea¬
son you should do this is that the screen-fill routine in line
1 speeds up considerably when memory isn’t tight, since
the display file is already padded out with spaces. The
POKE followed by NEW resets your RAMTOP address to
limit available RAM to 2K.
SYNC WARS With 2K RAM Instructions
1. Load Syntactic Sum Loader (SYNTAX newsletter,
Aug. 82) into your 2K machine, and RUN, followed by
NEW. (If you missed the Aug. SYNTAX, send us a self-
addressed stamped envelope for a copy of Syntactic Sum
Loader.— Ed.)
2. Type in the program as listed.
3. Check Syntactic Sum— it should equal 51036
(PRINT USR 18408). If it does not, check the program
for errors. Make sure you run Syntactic Sum in the FAST
mode.
4. Enter LET G$ = “SYNCWARS ” in immediate
mode (note space at end). Start recording and enter
GOTO 600. The program will SAVE to tape and stop
with error 2/610. Rewind tape.
5. Reset your computer by pulling the plug or flipping
the reset switch if you have one. This clears out the Syn¬
tactic Sum subroutine; there isn’t enough memory space
to run the game if any ML routines are present beyond
RAMTOP.
6. LOAD “SYNCWARS ” from tape (note the space
at the end). When loaded, computer will stop with error
2/610. Rewind the tape.
7. In the immediate mode (no line numbers), type in
the variables list. Do not CLEAR or RUN once you’ve
started entering variables. Arrays B$, C$, E$, and F$
store the graphic pictures of the invaders and their
destroyed counterparts; you may easily design your own
figures on graph paper (each picture is five print positions
tall and three positions wide) and then enter the strings
line by line into the appropriate arrays.
8. Again save the program (this time with variables
loaded) to tape, overwriting the first version. Program
starts when saved.
SYNTAX QUARTERLY/SPRING 1983
1 REM Y.^*:4NOT $TflB ,#RND| TRB
Vrndtrn
10 PRINT RT R,T; ; G*, , , , "BY
F.NACHBAUR" '
25 POKE 164-18,0
RY30 PRINT OT M,0; "PRESS P TO PL.
4-0 PAUSE U
50 RAND
100 LET 5=0
110 FOR C=P TO T
120 CLS
130 LET D = I NT (RNDiU)
14-0 LET E = INT (D-'T)
150 LET G= (D-T*E) *©+E
160 LET E=E*N-P
180 LET H=INT (RNDiU)
185 IF H=D THEN GOTO U+U
190 LET I = I NT (H/T)
210 LET K= (H-T*I) *© + I
215 LET I=I*N— P
220 PRINT USR 16514- ; RT H.O;H*
260 FOR R=P TO R
264 PRINT RT E+fi,G;C*(A)
268 NEXT R
270 PAUSE U-©*C
290 IF INKEY *="" THEN GOTO U*R
g00 IF INKEY*=R* IH+P) THEN GOTO
n3I®TIF INKEY* < >A* CD+P) THEN GOT
320 CLS
330 FOR R=P TO R
335 PRINT RT E+A , G; E* (R) ; RT I+R
D$ l R}
340 NEXT R
350 PRUSE U-©*C
IP INKEY*="" THEN GOTO U*R
Q3jPS^IF INKEY* < >R* (H+P) THEN GOT
40© FOR A=P TO R
404 PRxNT RT I+R,K:F*(R)
408 NEXT R
410 LET S=S+P
42© PRINT RT M,0;D*;S
430 PRUSE U
440 GOTO L
45© CLS
460 PRINT RT T,T;"TOO SLOW "
465 PRUSE U
47© GOTO L
490 PRINT RT I+P.K;"*B*“
494 PRUSE U
^36 IF INKEY *=A* (H+P) THEN GOTO
50© NEXT C
D|S| PRINT RT T , T ; “GAME OVER",,,
56© IF" S=T THEN PRINT
51836, SK ROM
~L
570 GOTO M
6©0 SRUE G*
6 I© GOTO T
SYNTACTIC SUM:
Notes for 2K Listing
1 Graphics on T,H,5,Y
10 Inverse space
30 “P, R,E,S,S, spc, P, token TO ,P,L,A,Y”
220 Screen fill
460 Token “SLOW”
490 Second character is inverse
560 Inverse video
Variables
(Enter in immediate mode)
LET L = 500
LET M=23
LET N = 6
LET 0 = 0
LET P = 1
LET Q = 3
LET R = 5
LETT = 10
LET U = 38
LET V = 90
LET W = 40000
LET A$ = “1234567890QWERTYUIOPASDF
GHJKL ZXCVBNM.” Note space between L
and Z.
LET D$ = “SCORE = ”
LET G$ = “SYNCWARS
LET H$ = “ ”
LET A$(30) =CHR$ 118
DIM B$(5,3)
DIM C$(5,3)
DIM E$(5,3)
DIM F${5,3)
LET B$(l) =“> <”
LET B$(2) =“E _ R”
LET B$(3)=“_F_”
LET B$(4) = “W6Q”
LET B$(5) =“Q7W”
LET C$(1)=B$(1)
LET C$(2) =B$(2)
LET C$(3) = _ 7 _ ”
LET C$(4) = “Q _ W”
LET C$(5) =“E R”
LET E$(l) = “ / ”
LET E$(2) =“< <”
LET E$(3) = “TE*”
LET E$(4) =C$(4)
LET E$(5) =C$(5)
LET F$(l) =“GOT”
LET F$(2) =“ * ”
LET F$(3) =“*_!_*”
LET F$(4)=F$(2)
LET F$(5) =“M*E”
Note space at end.
Space.
“Enter” character (replaces
space in A$).
Synclon array.
Syncloid array.
Broken Syncloid.
Destroyed Synclon.
Greater than spc less than.
Graphic E, inverse spc,
graphic R.
Inverse spc, graphic F,
inverse spc.
Graphic W, graphic 6,
graphic Q.
Graphic Q, graphic 7,
graphic W.
Inverse spc, graphic 7,
inverse spc.
Graphic Q, inverse spc,
graphic W.
Graphic E, normal spc,
graphic R.
Spc/spc
Less than spc less than .
Graphic T, graphic E,
normal *.
Second * is inverse.
SYNCWARS For 16K Machines
With a 16K RAM pack, you may POKE 16389,72 and
POKE 16388,24 then NEW to give you enough room for
Syntactic Sum plus the program and variables. The
PRINT USR address in this case is 18432, and you
don’t have to dump the ML routine before loading the
variables and starting the program going.
If you’d prefer not to POKE RAMTOP, but wish to use
your 16K machine, enter the program as written and add
the following lines:
SYNTAX QUARTERLY/SPRING 1983
15
1 REM SYNCWARS
Replaces old line
1 ML screen fill
220 FOR A = OTO M-P
230 PRINT “ . ’
240 NEXT A
500 FOR A = P TO RND* SQR W Replaces old line
500
510 NEXT A
520 NEXT C
NEW SYNTACTIC SUM = 53311
1
REM 5YNCURR5
1©
PRINT RT R , T ; ;G$, , , .
‘BY
F.NRCHBRUR'1
25
POKE 164 18 . O
30
PRINT RT MiO; “PRESS P TO PL
RY"
4-0
PRU5E U
50
RRND
10©
LET 5=0
110
FOR C=P TO T
120
CLS
13©
LET D=INT (RNDfU)
14-0
LET E=INT CD/T)
150
LET G= <D-T*E) *©+E
16©
LET E=E*N-P
180
LET H = INT (RND*U)
185
IF H=D THEN GOTO U+U
12©
LET I = INT CH/T)
210
LET K= CH-T*I) *0 + 1
215
LET I=I*N-P
22©
FOR R=0 TO M-P
23©
PRINT ’* ............... -
• . - -
24-0
NEXT R
26©
FOR R=P TO R
264-
PRINT RT E+R.. G; C$ (R>
268
NEXT R
27©
PRUSE U-G*C
298
IF INKEY $ = ** " THEN GOTO
U*R
300
IF INKEY $ =R $ C H +P > THEN
GOTO
U*T
310
IF INKEY$<>R$(D+P) THEN
GOT
O L-I
-
320
CLS
338
FOR R=P TO R
335
PRINT RT E+R,G;Ei(fl) ; RT
I+R
,K; C R>
34-©
NEXT R
35©
PRUSE U-Q*C
37©
IF INKEY $ = ** "" THEN GOTO
UiR
375
IF INKEY$Ofl$CH+P) THEN
GOT
O L-T
4-00
FOR R=P TO R
4©4
PRINT RT I +R ,K;F$ iH)
4-©S
NEXT R
41©
LET S=S+P
420
PRINT RT MjO;D$;S
43©
PRUSE U
44©
GOTO L
45©
CLS
460
PRINT RT T.T; "TOO SLOW
•*
465
PRUSE U
47©
GOTO L
42©
PRINT RT I+P , K; “ *fi*"
424
PRUSE U
426
IF INKEY $=R$ (H+Pi THEN
GOTO
U*T
5©0
FOR R=P TO RND*SQR U
510
NEXT R
53©
NEXT C
55©
PRINT RT T « T ; ** GRME OUER" , ,,
d$; Si
H$:
56©
IF S=T THEN PRINT
570
GOTO M
60©
5 RUE G$
61©
GOTO T
SYNTRCTIC SUM: 53311., SK ROM
This modification randomizes the length of time be¬
tween successive invader pairs, making the game a little
less predictable. The routine in lines 220-240, while tak¬
ing more memory than the MC screen fill (and therefore
unusable in the 2K version), is faster and allows the next
Syncloid to appear almost immediately, or delay for a
while, as determined by the dummy loop in lines
500-510.
Running the Program
The program starts automatically when loading from
tape. When playing the game be careful not to press the
SPACE/BREAK key; to do so will break operation.
CONTinue will not work to restart the program, making it
cheat-proof. If you hit BREAK by mistake, you can start
the program again by entering GOTO 0 (or GOTO O or
GOTO P).
ZX80s
Since the program runs in the FAST mode, it will run in
ZX80s with 8K ROM, even without video upgrade mods.
Minimum RAM requirement is 2K.
IK Machines
Finally, here’s a listing of the game which will run in IK
ZX81s and ZX80s with 8K ROM update. As with the 2K
version, you must load Syntactic Sum (if used) and then
type in the program; check Syntactic Sum, and when
Available from SYNTAX. . .
For computing beginners —
Crash Course in Microcomputers . $19.95
Covers hardware, machine language and
applications. Reviewed in SYNTAX, Oct. 1981.
Add $1.50 shipping.
ZX80 Pocket Book . $10.95
Includes ZX81 supplement. Covers Sinclair
BASIC, data and program listings.
Add $1.50 postage.
For advanced hardware/ software users —
Zilog’s Z80-Z80A CPU
Technical Manual . $7.88
Zilog’s Assembly Language
Programming . $15.75
Experiments in Artificial
Intelligence . $8.95
Add $1.50 postage.
SYNTAX back issues available, $4 each.
Call or write for our group subscription discounts.
SYNTAX • RD 2 Box 457 • Harvard, MA 01451
617 / 456-3661
16
SYNTAX QUARTERLY/SPRING 1983
correct save the program to tape. Then reset the machine,
load from tape, and enter the variables. Type GOTO 0 to
start the game. Don’t forget to save the program with var¬
iables, overwriting the first SAVE.
This version is more difficult, since you don’t have a
second chance to get the invaders. Also, the display is
considerably smaller and the invaders’ positions are not
staggered to match the layout of the keyboard. Note that
if the invaders appear at any of the last three positions in
the bottom row, you must hit to score.
Notes for IK Version
124 20 periods.
250 Graphics on R,E; E,R.
320 Graphics on 5,Y; 2 inverse Graphics on T,Y.
Variables
LET L = 500
LET P = 1
LET Q=2
LET R=4
LET T = 10
LET V = 90
LET A$ = “1234567890QWERTYUIOPASDF
GHJKL ZXCVBNM . . (LEN A$ should be 40)
LET A$(30) =CHR$ 118
To start, enter GOTO 0 or GOTO P. In this version, if
you hit the SPACE/BREAK key by mistake, it’s ok to
type CONTinue and keep going. If you type RUN by mis¬
take, reload the variables list and start with GOTO. You
may prefer to run this version in SLOW mode. SQ
li pIuse ST r'r;"syncuprS-
100 LET S=P -P
110 FOR C=P TO T
115 CLS
122 FOR E=Q TO T-P
124- PRINT " . .
126 NEXT E
130 LET E=INT (RND*R)
14-0 LET G = INT (RND *T>
150 LET D=T*E+G+P
160 LET E=E*Q
170 LET I =INT (RNDiR)
19© LET K=INT (RNDjT)
200 LET H=T*I+K+P
205 IF H=D THEN GOTO U+U
21© LET 1=1*0
250 PRINT AT E .GiQ; "T" ;TAB G*Q
' 270 PRUSE U
280 IF INKEY$=R$(H) THEN GOTO L.
-U
200 XF INKEY$< >R$ CD) THEN GOTO
L
300 CL-3
320 PRINT RT E ,GfO; " </u;TftB G*G
; "i V' ; RT i .. K *Q ; "HI" ; tab k
325 PAUSE U
33© XF INKEY$Ofi$(H) THEN GOTO
L_
4-1© LET S=5+P
4-20 PRINT RT I,K^O; 'T/’UTAB
; V'j 5
4-05 PRUSE V/S
5©0 NEXT C
510 PRINT RT T ,P; "YOU GOT ";S;"
SYNCLONS”
SYNTACTIC SUM: 29905.. 3K ROM
IIS INTERCOM PUTCR INC
T M
presents
A Full Line Of Quality
SOFTWARE
For Your TIMEX 1000
Or SINCLAIR ZX81
IC's new line of software includes action-packed,
challenging programs which put the user in the
pilot's seat of an air force bomber; into the
casinos of Las Vegas; behind the controls of a
nuclear missile launcher; alongside the President
as his bodyguard; in a lost spaceship, far from
earth; in command of a submarine destroyer,
and challenge him or her to other mind and
strategy games.
DEALERS AND DISTRIBUTORS
WELCOME
WE ACCEPT CALL ORDERS
.... .. WITH VISA OR MASTERCARD
Write or Mail to:
INTERCOMPUTER, INC.
P. O. Box 90, Prudential Center
Boston, Mass. 021 99 (61 7) 437-1 1 90
»— v— — — —order form—— — . — — ...
U. S. $~ T TOTAL-
10195
10195
1 0| 95
1 0| 95
10195
10|95
10l95
14l50
14|50
1 4| 50
10|95
14|50
59.95
109.95
179.95
All Programs require 16K RAM Sub Total 1 - 1 —
•Defective tapes will be replaced, # -
if returned within 3 days. *5% Mass. Tax
•Please allow 2 weeks for delivery. TOTAL
•Your order may be sent in more *Mass. Residents Only
than one shipment.
□ Check enclosed D Charge my credit card below
Name '
1002
Missile Launcher
1003 |
Jeopardy
1004 j
Vegas
1005
Demolisher
1006 i
Air Attack
Guard the President
1008 Combo PAK I _
1009 Combo PAK II
I - Combo PAK III _
1 1 01 1 Submarine
11012 "Combo PAK IV
! pQ01 Memopak 16 K RAM
P002 I Memopak 32 K RAM
Memopak 64 K RAM
I Company
City
Signature
Card Number
□ visa □ Maste
Expiration Date
SYNTAX QUARTERLY/SPRING 1983
17
SOFTSYIMC, #/VC.
THE WORLDS BEST PROGRAMS
THE WORLDS BEST PROGRAMMERS
JOIN THE FAMILY. CALL OR WRITE FOR A FREE TS1000/ZX81 CATALOG
AND PROGRAM LISTING AND OR DETAILS ON PROGRAM DISTRIBUTION
14 E. 34th St. NEW YORK, NEW YORK, 10016 212-685-2080
ffpl SOFTWARE— EDUCATION
v by Steven Walley, Sunnymead, CA
8K ROM/1 6K RAM
Geography
Review— U.S. States
Quiz Program
I recently adapted an idea for a program from Tab’s
The A to Z Book of Computer Games. The result is a
states quiz that reviews the geography of the U.S. It is a
good teaching tool for children and a good review for
adults.
The program requires the 8K ROM with 16K RAM and
works best in the FAST mode.
Your objective is to match a state (the program picks
one at random) to a list of 9 regions and 1 state capitol in
the United States. If you fail on your first try, the program
gives you a second chance. If you fail again, you get
another try later on in the quiz.
The program keeps giving you states to match until
you get all 50 right. When you answer all 50 states cor¬
rectly the program tells you how many guesses you took.
The first guess is free: the computer only counts a wrong
answer if you miss it twice. This helps not to discourage
children from completing the quiz. If you want to refer to
the quiz instructions at anytime, just push key I (for in¬
structions) and they will appear on the screen. To see
your score at anytime, push key S. To quit, push Q.
After ENTERing the program, hit RUN and ENTER.
The program is SAVEd under the title “USA”.
U.S. States Quiz uses the string slicing capabilities of
the Sinclair 8K ROM as the method of getting information
out about the 50 states. To speed up the program, the
most frequently used routines are at the beginning. The
program also makes use of the INKEY$ function instead
of INPUT followed by ENTER. This reduces the number
of keys you must press.
Listing 1 describes the variables used and their func¬
tions. Instructions for U.S. States Quiz are contained in
lines 8010-8090. To exit from the program, just push
BREAK.
Listing 1
A How many times (0 or 1) you missed the question.
B — How many questions you answered correctly.
C — How many questions you answered incorrectly.
D — The number of states you have been asked to
match.
E — Does the player have a name? (0 if no)
F — Random number (1 to 50) picks which state the
question is about.
G Counts the states to see if all have been answered
correctly.
A$(F, 1 to 16)— State data. The first element of the string
is the location (0 to 9) , the second is if it has been guessed
(1) or not (0) , the remainder of the string names the state.
B$ — Player’s name.
C$ — Key on the keyboard that has been pushed.
D$ — Name of the location picked.
E$ — Name of the correct location.
SQ
ig usr
20 C!_:5
30 GO SUB 9000
4-0 PRINT "URNT INSTRUCT JONS (V
OR N)
5© PRUSE 4-©0©0
GOT5N§l^f = ,'N" ™EN GOTO S0
§0 CL. 3
3© PRINT "UHRT IS YOUR NRHE7"
10Q INPUT B$
110 LET E = 1
la© LET F = INT (RNDiSB) +1
130 IF R$fF,2) <>"8" THEN SOTO 1
14-0 GOTO 1000
150 PRUSE 4-0000
160 LET C $ = INKEY $
IT© CLS
IF C$ = THEN GOTO S00©
130 IF C$="s" THEN GOTO 7000
=i00 IF C$ = "Q" THEN GOTO 6000
210 REM ERROR TRRP
220 IF C$ = "©*‘ OR C$ = " 1 " OR C$ = '
OR C$="3" OR C$ = "4-'' OR C$=''5'
005*C* = :,6‘' 9R CS = "7" OR Cl = "8" O
R C t = 3 THEN GOTO 25©
230 GOTO 100@
24-3 REM LOCRTION GUESSED
|Tp0 IF C* = "0” THEN LET D* = "REMO
F?S® IF C*="I" THEN LET D$-"PflCI
n|Z0 IF THEN LET D$=" HEXI
28© IF C$ = "3’' THEN LET D* = "GULF
_ Continued Next Page
SYNTAX QUARTERLY/SPRING 1983
19
290 IF C* = "4-" THEN LET D*="fiLRN
124© IF R$(F,1)="6" THEN LET E$=
TIC"
"CRNRDR"
30© IF C$="5" THEN LET D$="GRER
1250 IF fl$ CF. 1) ="7" THEN LET E$ =
T LRKES **
" CHRRLEST ON "
31© IF C$ = ** 6 " THEN LET D$ = "CflNR
1268 IF R$CF.. 1) ="3" THEN LET E$-
Dh"
"HISS . RIUER"
320 IF C $ = " 7 ** THEN LET D$ = ,,CHRR
127© IF R$ (F .« 1) = "9" THEN LET E$ =
LE5TON"
"WESTERN"
330 IF C$="S" THEN LET D$="MIS5
1280 GOTO 158
. RIUER"
199© REM RIGHT RNSUER ROUTINE
34-6 IF C| = ''9" THEN LET D* = "UE5T
2©0© PRINT "UQU, ";Bt
ERN"
2010 PRINT , ,D*; " MRTCHES
35© IF R$(F, 1) =C$ THEN GOTO 20©
,3 TO 16)
©
2020 PRINT "YOU PICKED THE RIGHT
36© IF R<>© THEN GOTO 478
RNSUER. "
3*70 PRINT "SORRY « ";B$
2©3© PRINT . , s , "PUSH RNY KEY (EX
36© PRINT E>$; " IS NOT THE MRT CM
CEPT SPACE) FOR THE NEXT STRTE."
TO"
2©4-© PAUSE 4.©0©0
39© PRINT R$CF.3 TO 16)
205© LET ft$(F.2)="l"
4-88 PRINT , , "YOU GET ONE MORE C
206© LET R=©
HRNCE TO MRTCH"
2078 LET B=B+1
4-1© PRINT fl$(F,3 TO 16)
2080 LET D=D+1
4-2© PRINT "TO THE RIGHT LOCRTIO
209© FOR G=1 TO 50
N — "
2100 IF fl$(G,2) ="0“ THEN GOTO 12
43© PRINT ./‘PUSH RNY KEY CEXCE
0
FT 5PRCE) TO TRY RGRIN."
2110 NEXT G
448 LET H= 1
2120 REM RLL 58 STRTES MRTCHED C
45© PROSE 40©00
ORRECTLY
46© GOTO I©©©
2138 CLS
4-7© PRINT "SORRY ";B$
214-0 PRINT "UERY GOOD ";B*
48© PRINT "YOU MISSED TWICE"
215© PRINT "YOU HRUE MRTCHED RLL
400 PRINT , E$
5© STRTES"
500 PRINT “UPS THE RIGHT RNSUER
2160 PRINT "CORECTLY."
FOR"
2170 PRINT , , ** ******THESE RRE YO
510 PRINT R$(F,3 TO 16)
UR SCORES*****"
52© PRINT * j , , "PUSH RNY KEY (EX
2180 PRINT , , , j "STRTES RTEHPTED
CEPT 5PRCE) FOR THE NEXT STRTE"
TO MRTCH D — I
53© LET C=C + 1
2190 PRINT , , " ST RTES MRTCHED COR
540 LET D=D+1
RECTLY " ; B
55© LET R=8
2200 PRINT ./'STATES MRTCHED INC
56© PRU5E 40080
ORRECTLY " ; C
578 GOTO 128
2210 PRINT ,,"******************
GO© REM INSTRUCTIONS
****************
100© CLS
2220 PRINT , , , , "TO PLRY RGRIN PU
1018 PRINT "HELLO ";B$
SH *’**."
102© PRINT RT 0.30ID
2230 PRINT ./‘TO END THE QUIZ PU
103© PRINT j , "WHICH LOCRTION WIL
SH " "Z" " . "
L MRTCH"
224© PRUSE 40088
1840 PRINT R$(F,3 TO 16)
225© CLS
1050 PRINT " ** *** ********** ** ***
2260 IF INKEY$="Y" THEN RUN
**************
2270 IF INKEY$="Z" THEN GOTO 229
1068 PRINT RT 6 , 11; "LOCRT IONS"
0
107© PRINT , ,"0) REMOTE (2
228© GOTO 2148
STRTES MRTCH"
229© PRINT RT I0..5; "GOODBYE **;B*
1080 PRINT "1> PRCIFIC C3 ST
230© STOP
RTES MRTCH) "
5990 REM STOPPING THE QUIZ
109© PRINT "2) MEXICO C3 ST
500© CLS
RTES MRTCH) "
6810 PRINT B$
1188 PRINT "3) GULF (4 ST
6020 PRINT ./’TO STRRT RGRIN FRO
RTES MRTCH) "
H THE BEGINNING PUSH ""X
111© PRINT “4) RLRNTIC (13 S
*5 m 6 ^ it
TRTES MRTCH) "
6830 PRINT j j. "TO CONTINUE THE OU
1128 PRINT " 5) GRERT LRKES C7 ST
IZ PUSH ""Y""."
RTES MRTCH) "
6040 PRINT ./‘TO END THE QUIZ PU
1138 PRINT "6) CRNRDR (4 ST
SH ""Z""."
RTES MRTCH) "
685© PRUSE 40000
1140 PRINT "7) CHRRLEST ON Cl ST
606© IF INKEY$=“X" THEN RUN
RTE MRTCHES) "
6878 IF INKEY $ = "Y ** THEN GOTO 108
1150 PRINT "8) MISS. RIUER (5 ST
©
RTES MRTCH) "
6880 IF INKEY $ = "Z" THEN GOTO 610
1168 PRINT "9) WESTERN C8 ST
8
RTES MRTCH) "
6098 GOTO 600©
1178 PRINT , , . . "PUSH FOR T
61©8 CLS
HE INSTRUCTIONS"
oil© PRINT RT 10.5; "GOODBYE " ; B $
1188 IF R$(F,1)="0" THEN LET E$=
612© PRUSE 52©
"REMOTE"
6138 STOP
119© IF R$(F,1)="1" THEN LET E$=
699© REM SCORE
"PRCIFIC"
7©0© CLS
120© IF R$ ( F .« 1 ) = "2" THEN LET E$ =
7810 PRINT 6$;", THESE RRE YOUR
"MEXICO"
SCORES-"
121© IF R|(F. 1) ="3" THEN LET E$=
782© PRINT .. , . ."STRTES RTTEHPTED
"GULF"
TO MRTCH ** ; D-l
1228 IF R$(F,1)="4" THEN LET E$=
7030 PRINT . . "STRTES MRTCHED COR
"RLRNTIC"
RECTLY " ; B
1238 IF R$ (F *1) ="5" THEN LET E«f* =
"GRERT LRKES"
Continued Next Page
20
SYNTAX QUARTERLY/SPRING 1983
orrIctlyNT-:c"STOTES mrtched inc
X®E® “PUSH ONY KEY (EX
LEPT SPfiCE) TO CONTINUE.”
70t>0 PAUSE 4-0000
7070 GOTO 1000
7990 REM INSTRUCTIONS
8000 CLS
5S1£=ERINT "THIS QUIZ WILL TEST
1°, IFc YOU CRN MRTCH R STRT
f UITH ITS LOCATION {REGION OR
gTOIE CAPITOL) IN THE U.S.
3020 PRINT "AFTER YOU SEE THE FI
RST STRTE QNTHE SCREEN*j*ittftjtt
************"
®®3© PRINT "PUSH 0-9 TO MRTCH TH
E STRTE SHOWN TO ONE OF THE
LOCATIONS SHOWN."
8040 PRINT "PUSH ""I"" TO SEE TH
E INSTRUCT IONSRGR IN . "
URSSCORE^ "PUSH *"S"" TO SEE YO
SeSglPRINT “PUSH ""Q"" TO END TH
?®X® PRINT "THE LOCATIONS RRE LI
5XED IN THE priority TO BE RNSWE
RED (EXAMPLE -IF fl STRTE BORDERS
BOTH CRNRDR RND THE GREAT LAKES ,
GREgT LAKESWILL BE THE CORRECT
fif1SWER BECAUSE XT IS HIGHER
UP ON THE LIST OF LOCATIONS. *'
3080 PRINT "**************»***.*«.
************"
§S2®..PRINT "NOU PUSH ENTER TO BE
is XN >
8100 PAUSE 4-0000
8110 IF E=0 THEN GOTO S0
8120 IF E < >0 THEN GOTO 1008
8990REMLOAD STATESiiiiiiiiTHE
FIRST ELEMENT OF THE STRING IS
THE LOCATION, THE SECOND IS IF
IT HAS NOT BEEN GUESSED (0) OR
IE IT HAS BEEN GUESSED (1) , THE
REURINOER OF THE STRING IS THE
NAME OF THE STATE.
9880 DIM R$(5©,16)
9010 LET A$ { 1) ="30ALABAMA“
9020 LET A* (2) ="00RLASKA"
90o0 LET A* (3) ="20ARIZONA"
904-0 LET R$ (4.) ="80ARKRNSAS"
LET A * ( 5 ) = " 10CAL IFORN IA "
9060 LET A* (6) =“90COLORADO"
9070 LET A$ (7) ="4-0CONNECTICUT"
9080 LET A$ (8) ="40DELAWARE"
J-ET AJ (9) =“30FLORIDA"
9100 LET A* ( 10) ="4-0GEORGIA"
9110 LET A$(11)="00HAWAII"
9120 LET A$(12) ="60 IDAHO"
9130 LET A$(13) ="50ILLINOIS"
014-3 -LET -R$-(-i4) ="50 INDIANA"
9150 LET A* ( 15) ="S0IOUA"
9160 LET A* (16) ="90KANSAS"
9170 LET A* ( 17) ="80KENTUCKY"
®Jg® FFT R* (18) ="30LOUISIANA"
9190 LET A* ( 19) ="4-0MAINE"
9200 LET A$ (20) ="4-0MARYLAND"
9210 LET A* (21) ="4-0MRSSACHU5ETTS
9220 LET A* (22) ="50MICHIGAN"
LET R* (23) ="50MINNESOTA"
924-0 LET A* (24) ="30MISSISSIPPI"
iif? FIX R* (25) ="80MISSOURI"
9260 LET R* (26) ="60MONTANA"
9270 LET A* (27) ="90NEBRASKA"
9280 LET A$ (28) ="90NEUADA"
9290 LET A* (29) ="40NEU HAMPSHIRE
^300 FFT R* (30) = " 40NEU JERSEY"
®310 Fil R* 131) ="20NEW MEXICO"
FiX fil!<32)="40NEU YORK"
9330 LET A* (33) ="40NORTH CAROLIN,
93^0 LET A* (34) ="60NORTH DAKOTA"
9350 LET A* (35) ="50OHIO"
9360 LET A* (36) ="90OKLAHOMA"
9370 LET A* (37) ="10OREGON"
R38® LET R$ (38) ="50PENNSYLUANIA"
9390 LET A* (39) ="40RHODE ISLAND"
9400 LET A$ (40) ="40SOUTH CAROLIN
9410 LET A$(41) ="90SOUTH DAKOTA"
9420 LET A$ (42) ="80TENNESSEE"
9430 LET A* (43) ="20TEXAS"
9440 LET R$ (44) ="90UTAH"
9450 LET A* (45) ="60UERMONT"
9460 LET A* (46) ="40UIRGINIA"
947® LET A* (4?) =" 10WASHINGTON"
9480 LET A* (48) ="70WEST VIRGINIA
949® LET A* (49) ="50UISCONSIN"
9500 LET A$ (50) ="90 WYOMING"
9510 RAND
9520 REM HOW MANY TIMES YOU HAVE
MISSED THE QUESTION
9530 LET A =0
9540 REM HOW MANY RIGHT
9550 LET 5=0
9560 REM HOW MANY WRONG
9570 LET C=0
9580 REM HOW MANY STATES HAS THE
PLAYER BEEN ASKED TO MATCH
9590 LET D = 1
960© REM NO NAME YET
9610 LET E =0
9620 RETURN
SYNTACTIC SUM: 20220, 8K ROM
We will pay
CASH
for non-exclusive rights to
manufacture and sell your
Timex/Sinclair educational and
entertainment programs.
DALLAS DEVELOPMENT SYSTEMS
7410 Stillwater
Garland, Texas 75042
(214) 238-1776
SYNTAX QUARTERLY/SPRING 1983
21
SOFTWARE— UTILITY
by Dan Platt, Edinboro, PA
8K ROM/4K RAM
POKEing
Directly To The
Display File
In SYNTAX newsletter (Nov. 81) a neat games pro¬
gram appeared called “MONXZER” (revised version
Winter 82 issue of SQ). But the graphics are sooooo
slooooow and take up sooooo much memory. How can
we avoid this tremendous memory consumption and de¬
lay with graphics?
First, it isn’t necessary to directly use PRINT or PLOT
statements. You can write directly into the display file,
the place in memory where the computer stores the infor¬
mation to be shown on the screen.
Try this:
POKE PEEK 16396 + 256* PEEK 16397 + 114,23
An asterisk should appear near top center of your screen .
(I will explain why later) . The display file’s memory seems
to be set up as follows:
Enter (Code 118) 32 bytes of text
Enter 32 bytes of text
Enter 32 bytes of text
Enter 32 bytes of text, etc.
Using the enter symbol as the first byte of each line
seems to key the video— without it the screen goes crazy.
So you shouldn’t write (POKE) into these locations. To
count out where to POKE a variable, add 33 for each line
past the first ENTER (code 118) plus the number of char-
we may use (you guessed it) machine coding! It is much
faster, and memory economical. Consider the following
program:
LD HL, (16396) ; first location for D _ FILE
LD BC,81 ; first position 2nd row, 15th col.
LD A, 23 ;23 is code for symbol *
ADD HL,BC ;HL points to 2nd row, 15th col.
LD (HL),A ;put in *
LD BC,33 ; displacement for 1 row.
ADD HL,BC ;next row
LD (HL),A ;put in next *
ADD HL,BC ;next row
LD (HL),A ;put in next *
ADD HL,BC ;next row
LD (HL),A ;put in next *
RET ;go back to main program
You can load this routine into a REM statement at line
1. (See also Machine Code Programs — Where and How
to Load Them by William Wentz, SQ, Winter 1982.) Enter
1 REM AAAAAAA. . . (three rows are enough). Then
POKE the following values in numerical order. For exam¬
ple, type POKE 16520,42 then press ENTER or NEW-
LINE. Then type POKE 16521,12 and press ENTER and
so on. Don’t put any line numbers before the POKEs.
acters (columns) over to be displayed.
CO «M6520,42
You may find the location of the first “Enter” by look- 16521 12
ing into the system variable D FILE (memory pair 16522 64
16396 and 16397) . Thus, we POKE the asterisk (symbol 16523 1
23 in the character set table) into the third row 3 x 33 and tD 16524' 8
the 15th column. The two PEEKs tell the computer n
16524,81
16525,0
where to look for the start of the display file. Adding ^ * 16526 62
3*33 + 15, or 114, tells it to move to the third row, 15th ^^^16527*23
column. So the location to POKE the asterisk symbol 16528 9 ^
column. So the location to POKE the asterisk symbol 16528 9 16539 2<
given by: fJTLj A 16529|llS\
PEEK(16396) +256*PEEK(16397) +3*33 + 15 £.O0C. 16530,1 \
I don’t recommend using PEEKs and POKEs for speed t, , ...
hpn pntpr thiQ li np*
and certainly not for memory conservation. However,
they do demonstrate how to get into the display file. Now 10 LET A = USR 16520
16531,33
16532,0
16533.9 *
16534.119
16535.9
16536.119
16537.9
16538.119
16539,201
22
SYNTAX QUARTERLY/SPRING 1983
Four asterisks will appear very fast (even in SLOW mode)
when you RUN this two-line program.
I recommend learning how to use machine code for
these kinds of problems. Check out TRS-80 Assembly
Language Programming by William Barden for a discus¬
sion of various techniques (useful for any assembly or
machine language) and Z80 Users Manual by Joseph J.
Carr for a more detailed discussion of the instructions.
(Look out! His codes in binary aren’t always correct!
These are contained in the back of the TRS-80 text.)
Lastly, we may look at the pixels and how to address
them in machine code. Each character block on the
screen is split up into four segments. If we label bits from
least to most significant beginning with one:
_ 87654321
00000000
We see that all zeros are blank (white) , a 1 in bit one turns
on (blackens) the upper left hand corner, the second bit
the upper right, and the third the lower left.
We thus see that the addressing used by the PLOT in¬
struction is somewhat more complicated than at first
glance. Also, if you know what symbols go where (not
doing mathematical graphs), you just need to store them
in a table and use a machine-coded segment to place
them in position.
In closing, I’d like to indicate that 1) machine code isn’t
complicated; 2) it is tedious; 3) it is very fast; 4) it is very
memory efficient; and 5) some programming problems
involving graphics display are best solved with machine
coding.
= 00000000
E
3
= 00000001
= 00000010
= 00000100
We can form graphics symbols by darkening combinations
of pixels:
= 00000011
If you wondered what happened to the lower right hand
pixel, it’s coming right up. We may form an inverse image
by putting a 1 in bit 8:
(Ed. note: This program requires 4K RAM or more to
B GENERAL SYSTEMS CONSULTING
2312 Rolling Rock Drive
Conley, Georgia 30027
SINCLAIR ZX81 and
TIMEX SINCLAIR 1000 SOFTWARE
16K minimum configuration
Designed to help monitor your finances.
1. Amortizations . 9 95
2. Bar Charts . 9 95
3. Annuity Evaluation . . 9 95
4. File Manager . 9.95
5. Bank Statement Balancer . 9 95
6. Checkbook Simulator . 9.95
7. Depreciation Straight Line . 9.95
8. Depreciation Declining Balance . . i . . 9.95
9. Depreciation (ACRS) . . ... 9.95
10. Diet Plan . \ . . 9 95
11 Home Budget . 9 95
12. Home Inventory . 9.95
13. Home Payables . 9.95
14. Home Equity Evaluation . 9.95
15. Real Estate Investing . 9 95
16. Savings/Investments Analysis . 9.95
17. IRS 1040 (Long Form) . . 9 95
18. IRS 1040 A (Short Form) . 9.95
19. Income Tax Projections . 9.95
Circle selections and fill out form beiow:
123456789 10
11 12 13 14 15 16 17 18 19
Number of items selected _ (5) 9.95 . .
Postage/Handling 1.50 . .
Total: _
NAME _ _ _
ADDRESS _ _
CITY/STATE/ZIP _ _
SYNTAX QUARTERLY/SPRING 1983
23
SOFTWARE— MATH
by R.A. Woodall, Laughlintown, PA
8K ROM/16K RAM
Simultaneous Linear
Equations and
Matrix Inversion
Solves simultaneous linear equations or inverts an N*N
matrix by forward and backward row reduction. A delight
for amateur mathematicians.
Given a simple system of linear equations, for exam¬
ple, if X + 2Y = 5 and X = 2, find X, your favorite
junior high school whiz would no doubt arrive at the cor¬
rect answer before you could even find the tape to load
your computer. But as the size of the problem grows to
involve more than about three variables, the solution can
become quite tedious and prone to error. There is also
the chance that after much arithmetic you will find that no
unique solution to the problem exists. So if you have say
a 10 by 10, you can bet that your ZX/TS will beat any
pencil pusher several times over.
Matrix algebra is a little more complex, but the row
reduction method is essentially the same as for simultane¬
ous equations and it is convenient to include both in one
program. I’ll not even begin to explain why one would
want to invert a matrix, but matrix inversion is rather akin
to taking the joint reciprocal of a specific array of num¬
bers. If you multiply the inverted matrix by the original
matrix, you see the operation is similar to the simple
1/X*X = 1.
To use this program, just type it in and RUN. It is fully
prompted, so just enter the correct responses. The pro¬
gram starts by asking for the type and size of problem,
sets appropriate dimensions and prompts the necessary
input. I calculate that 16K RAM will handle at least a
25 x 35 matrix or about 50 simultaneous linear equa¬
tions. During input the coefficient matrix is augmented as
necessary by either the output matrix for equations, or an
identity matrix for inversion. You can make corrections
after entering all data. To exit, just answer N after your
problem is solved.
Forward row reduction proceeds by stepping across
the columns and down each row (along the diagonal),
selecting at each step a sub-row suitable for reducing each
10 PRINT “THIS PROGRRM SOLVES"
2© PRXNT "SIMULTANEOUS LINEAR”
30 PRINT "EQUATIONS (E) OR"
4-0 PRINT "INVERTS AN N*N MATRI
X C 13 "
SO PRINT
S© PRINT "WHICH ONE , (E) OR (I
7© INPUT
S0 PRINT Q$
O© IF ©$="E" THEN LET H=1
10© IF ©$="I" THEN LET H=2
110 IF Mol AND M<>2 THEN GOTO
60
120 PRINT
130 PRINT "GIVE SIZE? ";
14© INPUT N
IS© PRINT N
1S0 IF M=1 THEN LET M=N+1
17© IF M=2 THEN LET M=2*N
180 DIM X(N,M)
190 SCROLL
2©@ PRINT "ENTER COEFFICIENTS"
205 SCROLL
218 IF M=N + 1 THEN PRINT "AND OL
Tpirr ARRAY"
220 SCROLL
230 PRINT "RQU COLUMN"
24-0 SCROLL
250 FOR R=I TO N
260 FOR C=1 TO N
27© PRINT " " ; R; TAB 8; C ,
288 INPUT X*R,C)
200 PRINT X (R, C)
205 SCROLL
30© NEXT C
310 IF MoN + 1 THEN GOTO 380
33© PRINT " " ; R; " OUT",
350 INPUT X < R , H 3
3S0 PRINT X(R,M)
370 GOTO 30©
380 LET X (R , N+R3 =1
300 SCROLL
4-08 NEXT R
4-18 SCROLL
4-20 PRINT "ANY CORRECTIONS CY3 7
430 INPUT Q$
44© IF Q$<>"Y" THEN GOTO 508
45© SCROLL
4S© PRINT "WHICH ROW?
47© INPUT R
48© PRINT R
40© SCROLL
Continued Next Page
24
SYNTAX QUARTERLY/SPRING 1983
50© PRINT “ WHICH COLUMN {OUT IS
N + l) *?
510 INPUT C
520 PRINT C
530 SCROLL
54-0 PRINT "ENTER UflLUE? " :
550 INPUT X (R,C)
560 PRINT X (R, C)
5S0 GOTO 4-1©
59© CLS
60© REM FORWARD EL IMINRT ION
61© FOR C = 1 TO N — 1
62© LET A=©
630 IF X{C,C) < >© THEN GOTO "730
64-0 FOR R=C + 1 TO N
650 IF X (R,C) =0 THEN GOTO 720
66© FOR 1=1 TO M
670 LET T = — X iR,Ii
680 LET X tR . I) =X (C, I)
69© LET XCC.I)=T
700 NEXT I
710 GOTO 73©
72© NEXT R
730 LET R=XiC,Ci
74-0 IF R=0 THEN GOTO 124-0
750 FOR R=C+1 TO N
760 LET B=X(R,C) /fl
770 IF B=0 THEN GOTO 81©
780 FOR I=C TO M
III Nl^TXiR IJ =X{R'I) -B*X(C,I)
810 NEXT R
82© NEXT C
830 REM CHECK DETERMINATE
84-0 LET D = 1
350 FOR 1=1 TO N
860 LET D=D*X(I,I)
87© NEXT I
880 IF D=0 THEN GOTO 1240
890 REM BRCKURRD ELIMINATION
9©0 FOR C=N TO 2 STEP -1
910 LET A=X (C,C)
920 FOR R=C-1 TO 1 STEP -1
930 LET B=X (R,C) /A
94© FOR I=C TO M
III nIxt*!^1* =XtR'I> ~B*XtC,I>
970 NEXT R
980 NEXT C
990 REM PRINT RESULTS
100© IF M=2*N THEN GOTO 110©
1010 PRINT "THE INPUT ARRAY IS "
1020 PRINT
1030 FOR 1=1 TO N
<ltl)PRINT = "iXtI,M)/X
1050' NEXT I
1060 GOTO 118©
| 10® PRINT "THE INUERTED MATRIX
11 1© PRINT
1120 PRINT "ROW COLUMN-
1130 FOR R = 1 TO N
1135 PRINT
1140 FOR C=1 TO N
f 15® PRINT " "JR; TAB 7JC,XCR,N+C
* / X ( K .i R J
1160 NEXT C
1170 NEXT R
118© PRINT
1190 PRINT "DETERMINATE IS : " , D
1200 PRINT
1205 PRINT "RUN AGAIN (YJ ?"
121© INPUT 0$
1215 CLS
122© IF Q*="Y" THEN RUN
1230 STOP
1S40^PRINT "SINGULAR COEFFICIENT
1250 PRINT "NO UNIQUE SOLUTION"
1260 GOTO 120©
SYNTACTIC SUM: 58033, 8K ROM
other sub-row, moving the entire row to the top of the
sub-matrix if necessary, and performing the reduction. If
the computer finds a row it cannot handle, the program
recognizes the singularity of the coefficient matrix and
stops. Completion of the forward reduction sequence
produces an upper triangular coefficient matrix and its
determinant is found as the product of the diagonal
elements.
If the determinant is not zero, the system can be
uniquely solved and backward elimination proceeds in a
manner similar to the forward steps. Upon completion
the answers are found by dividing each row element of
the augmented matrix (which has been similarly operated
upon) by the diagonal coefficient in the same row. The
computer then prints the answers in logical sequence, but
larger problems will require CONTinues when the screen
is full. Finally, the determinant is printed and you can re¬
run the program.
Since, as usual, one “keypunch” error can throw the
whole program into a cocked hat, I include a couple of
test examples after the program listing as well as a practi¬
cal example of the use for simultaneous equations. Have
fun!
Simultaneous Equations:
Suppose you have four programs, each containing a
number of PAUSE statements (P), several loop (L) state¬
ments, several other operational program lines (O), and
(N) characters to be printed. You time the completion of
each program and solve for the time each element takes.
You can then use the answers to predict how long similar
programs will take to run.
Prog
* P
L
N
O
Time (sec)
1
15
26
18
31
6.2
2
28
17
15
23
5.4
3
19
42
7
36
2.9
4
11
21
12
19
4.2
The answers
are: X-l
=
.017664834
sec.
-2
=
.011355478
-3
=
.32093198
-4 = .0044190484
Matrix Inversion:
The following matrix is singular: 4 1 2 6
1 2 4 1
0-1-21
0 6 12 0
The inverse of the matrix: 1 0 1 is 0 0 1
3 10 0 1-3
100 10-1
SQ
SYNTAX QUARTERLY/SPRING 1983
25
j=^i SOFTWARE— HOME/BUSINESS _
by Michael Roberts, Des Moines, IA 8K ROM/16K RAM
ZX/TS
Home
Budget
One of the first applications that come to mind
when you get a personal computer is managing
your home finances. However, when 1 got a copy of
Sinclair’s Home Budgeter, I was disappointed. It was fast,
with good displays, but difficult to follow and modify. It
seemed to do the wrong things. I wanted a program to
keep track of my monthly expenditures in a variety of ac¬
counts as well as annual totals for expenditures by item
and as a whole. This Budget version resulted.
Type in Home Budget as listed. Before using it the first
time, save blank copies on tape by entering RUN 9900.
These copies are self-running from then on.
To use Home Budget, just follow the prompts. The
prompts should be adequate to avoid errors, but most in¬
put routines will check for an invalid input and reject it. If
you do manage to stop the program for some reason,
you can re-enter without losing your data by entering
GOTO 1. Do not use RUN or you will lose all your data.
To start over, enter GOTO 100. It’s good to leave your
program line cursor at line 1, so if the listing comes up on
the screen you see a reminder not to RUN.
Home Budget handles up to 75 differently named ac¬
counts of up to 12 characters. When you first set up a
budget, consider setting aside two or three extra accounts
with no budget figures, in case you want to add an item
or two to your budget later. You can call up accounts by
any unique part of their name or their number.
After you set up your accounts the program gives you
a menu (see Figure 1). This menu accesses all the pro¬
gram’s functions.
My version of Home Budget offers some features you
may like whether or not you need the whole program. The
subroutine at lines 10-38 converts the floating point
variable M to M$, a dollar-and-cents figure as we like to
view it. If M is negative, the routine at lines 20-26 changes
the string to inverse characters. Printing in inverse makes
the negative numbers stand out clearly in a list.
Lines like 1645 and 1660 provide another nice feature
throughout the program, right-justifying the figures for
easier reading and neater printout.
BUDGET NRhE .
1: SUMMRRY OP RL.L. RE-COUNTS
2: DETAILS OF ONE ACCOUNT
3: ENTER NEU INFORMATION
4-: CHANGE R BUDGETED AMOUNT
S: CHANGE /CORRECT THE NAME OF
ACCOUNT
S: SAUE THE PROGRAM
7: EXIT THE PROGRAM
LAST UPDATE: NEU TRPE _
Figure 1
I like to run Home Budget as listed, but you can get
faster results by running your computer in FAST mode all
the time. To run Home Budget in FAST, delete all
SLOW and PAUSE statements. Change lines like 1695
to INPUT X$.
Line 1 is the Bytes Remaining routine from SYNTAX
newsletter, Oct. 82. I like to include it in most programs
to see how much memory is left.
Lines 100-345 initialize and identify variables.
Ed. note: For ease in reading the listing, here are the texts
of lines in inverse video:
Line Text
2 space asterisk space asterisk space DO NOT
RUN space asterisk space asterisk space
asterisk 3 spaces IT WILL KILL ALL
YOUR DATA 8 spaces USE 2 spaces
“GOTO 1” 2 spaces TO RESTART 4
spaces COPYRIGHT (C) 2 spaces OCT. 7,
1982 2 spaces BY MICHAEL ROBERTS -
DES MOINES, IA
26
SYNTAX QUARTERLY/SPRING 1983
4
space TO BEGIN A NEW FILE 3 spaces
ENTER 2 spaces “RUN 100” 16 spaces
110 ENTER THE NUMBER OF BUDGET
ITEMS
250 ENTER THE NAME OF THIS PROGRAM
1610 ANNUAL BUDGET 4 spaces SPENT TO
DATE 2 spaces
1680 “Z” = COPY 2 spaces “C” = CONTINUE 2
spaces “M” = MENU
1730 MONTHLY BUDGET:
1865 OVERSPENT.
1880 “Z” = COPY 2 spaces “C” = CONTINUE 2
spaces “M” = MENU
2010 DETAILS OF AN ACCOUNT
2040 BUDGET/MONTH:
2350 9 spaces Z = COPY 3 spaces M = MENU 8
spaces
2510 6 spaces NEW INFORMATION ENTRY 5
spaces
2520 same as 2510
2550 (ENTER “l”OR “2”)
2590 (USE THE 3 LETTER ABBREV.)
2680 5 spaces ANOTHER ENTRY? (Y/N) 7
spaces
3010 CHANGE A BUDGET FIGURE FOR
ACCT.
3050 (ENTER “l”OR “2”)
3520 PRESENT NAME:
3560 NEW NAME:
4025 REMEMBER TO MAKE A “SPARE
COPY” 1 space
4550 NOT SQ
SYNTAX QUARTERLY/SPRING 1983
27
105© PRINT AT 5,2; ”2: DETAILS OP
ONE ACCOUNT “
1060 PRINT RT 7,2; *3: ENTER NEW
INFQRMRT ION"
107© PRINT RT 2,2; “4: CHANGE R 6
UDGETED AMOUNT “
1060 PRINT RT 11,2; "'5: CHRNGE/CO
RRECT THE NAME OF " ; T AB 5; "ACCOUN
5: CHANGE/CO
HB 5; “ RCCuUN
1065 PRINT RT
1 ©2© PRINT RT 15,2; *'6: 5AUE THE
PROGRAM “
110© PRINT RT 17.2,‘ ”7: EXIT THE
PROGRAM"
1101 PRINT RT 19 . i; * '
11©5 PRINT TAB 2; "LAST UPDATE: “
; 0$
111© PAUSE P
1X20 LET X$=INKEY$
113© IP X$ = "“ OR CODE X $ < 26 OR C
ODE X$>35 THEN GOTO 111©
1135 CCS
114© GOTO 5 -1-500 ^UAL X$
150© REM S ^SUMMARY * *
1510 PAST
152© DIM 5 (Nl)
1525 DIM T ( 14- )
153© FOR 1=1 TO Nl
1535 FOR «J = 2 TO 13
154-© LET 5(1) =5(1) +D(I,J)
154-5 NEXT U
155© NEXT I
1560 FOR 1=1 TO 13
1565 FOR <J= 1 TO Nl
157© LET T(I)=T(I) +D(J#I)
1575 NEXT U
156© IF I>1 THEN LET T ( 14- '! =T ( 14- }
+T (I)
1565 NEXT I
1590 SLOU
1600 FOR 1=1 TO Nl STEP G
1605 FOR U=© TO 9 _
1610 IF U=© THEN PRINT AT 0,©; "S
1515 IF J + I>N^MENGOT^680
162© PRINT N$(<J + I)
1630 PRINT TAB 6
1635 LET M=i2*D CI+U, 1)
164-0 GOSUB G
164-5 PRINT TAB K 15— LEN M$);M$..**
1650 LET M=5(I+d)
1655 GOSUB G
1660 PRINT TAB (2S-LEN H*> ; M*
1670 NEXT U _ _ _
^6 6 0^
1J6 9 0 PAUS^f" "
1695 LET X $ = INKEY $
17©0 IF CODE X$=118 OR X$=“H“ TH
EN GOTO S
1705 IF X$="2" THEN PRINT AT 21,
0; "
1710 IF X$=“Z“ THEN COPY'
1715 IF X$=“Z“ THEN GOTO 1660
1720 CLS
1725 NEXT^ I ■ HI II II ■
1735 LET M=T(1)
174-0 GOSUB G
174-5 PRINT H$
1750 PRINT
1755 PRINT “SPENT IN “ ; TAB 12; “AM
OUNT “ ; TAB 20; “ “ “ + “ “ =B AL ANCE “ ; T AB
0; “MONTH OF “ ; T AB 12; “SPENT “; TAB
20 ; - " “B“ “ =DEP IC IT “
1757 PRINT
1760 FOR^2 TO 13
1765 LET M=T(I>
1770 GOSUB G
1775 PRINT TAB 2 ; O* ( C 1-2) *3+ 1 TO
( 1-2) #3+3) ; TAB 10; "$";TAB (19-L
EN M$) ; M*;
1760 LET H=T(1)-UAL M$
1765 GOSUB G
1766 IF M > =0 THEN PRINT TAB 20; “
1787 IF M <0 THEN PRINT TAB 20; "E
1790 PRINT TAB (31-LEN . MS
1795 NEXT I
1799 LET T=©
1600 FOR 1=2 TO 13
1605 LET T=T+TCIi
1310 NEXT I
1820 PRINT , , “TOTAL ANNUAL BUDGE
T:
1825 LET M=X2*T(1>
1330 GOSUB G
1835 PRINT TAB (31-LEN M$) ; M$
1S4-© LET M=T
134-5 GOSUB G
1850 PRINT “TOTAL SPENT TO DATE:
$“;TAB (31-LEN
1655 LET M=12*TC1)-T
I860 IF M > =© THEN PRINT “BALANCE
LEFT : “ ,
1865 IF M < 0 THEN PRINT mfeMggl
1670 GOSUB G
1875 PRINT TAB 21;“$“;TAB (3I-LE
ISsl^RINT RT =>i ______
1395 LET X * = INKEY &
190© IF CODE X$=118 OR X$=“M“ TH
EN GOTO I©©©
1905 IF X$=“Z“ THEN PRINT AT E . ©
1910 IF X$=“Z“ THEN COPY
1915 IF X$=“Z“ THEN GOTO I860
1920 GOTO S
2000 REM * ^ANALYSIS S*
2020 GOSUB L
2030 PRINT Y$ _
204-0 print t BHaBBaKaam
204-5 LET H=DCY%±>
205© GOSUB G
2055 PRINT M$
2056 PRINT
2©60 PRINT “MONBAMT SPEf
CElfiCCUM BAL “
2070 PRINT L$
2S75 LET T=DCY'.15
2076 LET %J =©
203© FOR 1=2 TO 13
209© PRINT Q$C(I-2)*3+l
BALANl
2075
2076 I
2©30
209©
*3+3)
2100
2105
2110
2120
2100 LET M=DCY.I>
2105 LET U=U+M*
2110 GOSUB G
2120 PRINT TAB 12-LEN H$;M$;
2130 LET M=T-D(Y',X)
214-0 GOSUB G
215© IF M>=© THEN PRINT TAB 13;“
+ “ t
216© IF M<© THEN PRINT TAB 13; “E
2160 PRINT TAB 22-LEN M$;M$;
2185 LET M =T * ( I - 1 ) -U
Continued Next Page
28
SYNTAX QUARTERLY/SPRING 1983
2190 IF M<0 THEN PRINT TRB 23;
a 195 IF M>=© THEN PRINT TRB 23
+";
2200 GOSUB G
221© PRINT TRB 32-LEN M*; H*
2215 NEXT I
2219 PRINT
2220 PRINT "RNNURL BUDGET: " ."t
2225 LET M=T*12
2230 GQ5U5 G
224-0 PRINT TRB 25-LEN M$:M$
2250 PRINT •‘SPENT TO DRTE:
2250 LET M=U
22?© GOSUB G
2280 PRINT TRB 25-LEN M$;MS
2290 PRINT "BRLRNCE;",
2300 LET M=T*12-U
2310 IF M>=0 THEN PRINT "+";
2320 IF M <0 THEN PRINT "H" .
2330 GOSUB G
234.0 PRINT TRB 25-LEN M
2350 PRINT RT 21.0;
2360 PRUSE F
2365 LET Y*=INKEY*
2375 IF Y* = **Z" THEN COPY
§380 IF Y*="Z" THEN GOTO 2350
2390 CLS
24-00 GOTO S
2500 REH **NEU INFO**
2505 CLS
2510 PRINT
E
X
F X*
2555
ET X
R
R
R
2600 INPUT Y*
2505 FOR 1=0 TO 11
?6THENFGOTO°*6a!*3> +1 T°
2515 NEXT I
2520 PRINT “UHRT?"
2621 GOTO 2590
2625 LET 1=1+2
ft?™ “ENTER THE RHOUNT : "
264-0 INPUT <J
2650 IF U <0 THEN GOTO 2590
2660 IF X =2 THEN LET J=-U
2670 LET D (Y , I) =D (Y . I) +U
2680 PRINT RT 21.0; *'*|
2690 PRUSE F
270© IF INKE>'* = "Y" THEN GOTO 25©
2710 GOTO S
2990 STOP
3000 REH * *CHRNGE BUDGET FIGURE*
3005 GOSUB L
3010 PRINT
?S^LPRINT * ' “ 1 « NEW MONTHLY F
I IGURE ,T RB 14-; •* OR **
iNNURL^OTRL"2 R CHRNGE IN T«E «
1 3050 PRINT TRB 6;
3060 PRUSE F
3070 LET X$= INKEY $
3075 IF X$ <>"1** RND X*<>**2" THEN
GOTO 3070
3080 LET X=URL X*
3090 PRINT "ENTER THE RHOUNT • "
3100 INPUT <J
3110 IF X = 1 THEN GOTO 3200
3120 LET J=J/12
3130 LET <J= INT (0*100) X100
si*® EET D <Y * 1} tY ■•
3 150 GOTO S
3200 LET D (Y , 1) =U
3205 GOTO S
3500 REM **CHRNGE NRME * *
3505ePRINTs"TO CHRNGE RN RCCOUNT
3510 GOSUB L
3520 PRINT •• Y*
3530 PRINT , , "ENTER THE NEU ' NRME
354-0 INPUT Y*
3550 LET N* CY .4- TO > =Y*
3560 PRINT ■ ";Ni(Y)
3570 PRUSE 250 *
3580 GOTO S
4-000 REM **SRUE**
llil SSI5T oiKTER TOMV'5 DnT= ■
|!!|«|!|^T ?T.5'0i -pREpbh^bpc
TO^TRRT^ RT al-0;’PRESS ENTER
4-035 PRUSE F
4-04-0 SftUE ©$
4050 GOTO S
4-500 REH **EXXT**
4-510 PRINT “RRE YOU SURE YOU URN
T TO QUIT THE PROGRRH WITHOUT
4520^PRUSE fNEU IHFORMfiT^"
4530 IF INKEY$0"Y" THEN GOTO 10
0
4-550 PRINT RT 10.. 0;"IF YOU CHRNG
E YOUR MIND. ENTER ""GOTO 1000”
* . DO gIS&g PRESS RUN . "
4560 GOTO 9999
5000 REM * *SERRCH* *
e®rccoSntT""ENTER THE nrme of th
-5020 INPUT Y*
5021 IF Y*="” THEN GOTO 1E3
5025 FRST
5030 IF LEN V$> 15 THEN LET Y*=Y*
( TO 15)
5035 LET Y=LEN Y*-l <
504-0 FOR 1=1 TO N1
5050 FOR J = 1 TO 15— Y
Y$=N$(I,J TO U+Y) THEN G
OTO 5100
5070 NEXT U
5080 NEXT I
5090 PRINT "NO SUCH NRME FOUND -
TRY RGRIN"
5095 GOTO 502©
5100 LET Y = I
5110 LET Y$=Nt(I)
5120 CLS
5 125 SLOU
5130 RETURN
990© SRUE "HOME BUDGET"
9905 RUN 10©
9999 STOP
SYNTACTIC SUM: 55339, 8K ROM
SYNTAX QUARTERLY/SPRING 1983
29
raj=a] HARDWARE INFORMATION
r-^11 t> by John Andrews, San Jose, CA
Getting
Your Head
Straight
If you’re not a tape recorder buff, you may not know
the term azimuth as it applies to recorders. If you do,
you may have some inkling as to what follows. In either
case, you may learn something crucial to computing and
storing programs on tape.
In simple terms, “azimuth” is a line of direction.
“Azimuth alignment” related to tape recorders refers to
the line of direction of the gap in the record head pole
pieces (or iron). Sometimes you can’t see this tiny gap
with the naked eye, but it is always there. (In some
modern recorders the gap is filled with ceramic or other
material to prevent tape oxides from getting into the gap,
causing a magnetic short and subsequent loss of volume.
This problem can cause recording malfunction. For the
moment, let’s stick with azimuth alignment.) Figure 1 il¬
lustrates a record/play head, locating the gap and
azimuth.
I
I
I
Figure 1.
Note that the gap runs vertically (top to bottom) on the
head at right angles to the direction of tape travel. This is
the crux of the matter. Just how precisely you maintain
this 90-degree relationship determines the high frequency
response of the recordings. With voice recording, high
frequency response is not critical. With music, it depends
on how important you think it is to hear the high pitch
tones in your music. With computer data tapes, however,
it is crucial that high frequencies do not get lost. Com¬
puter data on tape is all relatively high frequency. Your
tape equipment must respond properly to the high fre¬
quency signals from the computer circuits or data will be
lost and you will have problems.
So, right about now, some of you lucky ones are say¬
ing “Well, that’s all very interesting but my tapes SAVE
and LOAD fine. So why should this concern me?” Well,
here are some reasons why.
If you never intend to exchange tapes with other
people, then azimuth alignment is not such a concern. As
long as tapes are recorded and played on the same
recorder, even with poor azimuth alignment, the head
alignment appears good to the tape. But, put that same
tape on a recorder with different azimuth angle and the
high frequencies will be reduced — maybe just slightly or
completely lost. At some point, you can’t load from the
tape anymore. Your ability to buy or trade taped pro¬
grams is seriously impaired unless everybody involved
has correct azimuth alignment on their recorders.
Also, if you put off aligning your recorder head you will
create a giant re-recording problem for yourself. If you
change your azimuth down the line somewhere, you
won’t be able to load previously recorded tapes. Obvi¬
ously the best time to check and realign is as soon as pos¬
sible so you don’t build up an extensive tape library prior
to setting your heads straight.
What it boils down to is this— any tape not recorded or
played back on machines with correct (90-degree)
azimuth alignment will probably work poorly, if at all.
For best results, before you proceed with alignment,
clean and demagnetize the heads.
Now, the question is, how to align your azimuth?
Several companies market test tapes made specifically for
this function. The most likely place to get one is a store
catering to audiophiles. A test cassette typically provides
several recorded tests, including timing, wow and flutter
30
SYNTAX QUARTERLY/SPRING 1983
as well as azimuth alignment. The alignment portion con¬
sists of several tones preceded by voice announcements
of their frequencies. They begin with relatively low tones
and increase with each test. For example: test one might
be a 500-cycle tone; test two, 1000 cycles; test three,
3000 cycles, and so on up to 10,000 or 15,000 cycles.
Flay a test track on your recorder and listen to the tones
after each announcement. If you can’t hear the tone after
an announcement you have passed the limit of your
recorder’s high frequency response. If this occurs at a
relatively low frequency, say 2000 cycles, you have a
problem. If you can hear 5000 cycles or above, you are
in pretty good shape.
Due to wide variations in recorder design, it is impos¬
sible to cover all possible variations here, so a general il¬
lustration will show you where to find pertinent items on
recorders. You may have to adjust your thinking to relate
the illustrations to your specific recorder’s physical layout.
In this regard, the basic problem is gaining access to the
adjusting screw (E).
Figures 9 and 10 are top views of a typical recorder
without a cassette inserted. Figure 9 shows how the
heads retract (dashed lines) under the housing top when
Figure 9.
SPINDLES
or ®
CASSETTE WELL
NOTCH
r ^
t-J - i. » A."
K
REC.
REW.
PLAY
F.F.
STOP
no keys are depressed. It also shows the access notch (or
hole) to the head adjusting screw. Figure 10 shows how
the heads move out into the cassette well when you press
the play key. When heads are in this position the ad¬
justing screw is accessible through the notch (or hole) in
the housing. On some recorders without the notch you
reach the screw by inserting a tiny screw driver on a slant
past the edge of the tape well.
If on your recorder, you insert the cassette in a trap¬
door and then close the door (Figure 11), there almost
has to be an access hole because the entire top surface
closes to play the tape. Sometimes a metal foil label
covers the hole. Peel up the label to gain access.
Figure 10.
REC./Play head
Erase head \ A .
^ \ Azimuth
y 1 adjusting screw
r""i
1
• 1 • •!»! J
Depressed
_ V _
IBBBDBI
If you find no access to the screw (E), you can do one
of two things: remove the recorder housing, make the
adjustment, then reassemble (NOT recommended for
novices); or make a hole (this is easier, but be careful).
To make a hole, locate the screw position exactly with
the heads in play position (Figure 10) and mark the loca¬
tion. Retract the heads (Figure 9) and make a hole in the
housing at the marked location . Use great care not to dam¬
age the head or mechanism in the process— do not let
chips fall into the recorder, make them fall away from it.
To adjust the azimuth: play the test track with the
highest tone you can hear (test tapes come with user in¬
structions). As it plays, adjust the tilt of your recorder’s
head to the point that gives the loudest volume. Then,
play the track you couldn’t hear before. If you can hear it
now adjust the head tilt during this track for maximum
volume. When you achieve the loudest volume on the
highest tone track you can hear, you have correct
azimuth alignment.
SYNTAX QUARTERLY/SPRING 1983
31
One note of caution. Don’t try to make your own test
tape or use a copy of one. You can’t be sure of the head
alignments involved with the copy recorders and a
misalignment could result. Test tapes are laboratory stan¬
dard aligned and you must maintain this standard to
make the concept work properly.
Figure 2, 3, and 4 illustrate (exaggerated for clarity)
good and bad azimuth alignment as well as typical head
mounting scheme. These sketches show the head as if
you were inside the cassette, looking through the tape at
the face of the head.
Head mounting flange A fastens to spacer post B with
screw C. Spring D replaces spacer post B on the opposite
side of the head. Adjusting screw E up or down against
the spring changes the tilt of the head assembly. Thus,
the azimuth angle changes relative to the tape edge.
Adjusting screw E would normally not require more
than a half turn in either direction to correct the azimuth
alignment. Usually a very slight amount of turning will do
the trick— about one-eighth of a turn is ample.
In some cases spacer B and spring D may be reversed,
or the whole setup may differ, but the principle remains
the same. The manufacturer also sets the azimuth the
same way you do it. (Sometimes they don’t do it as ac¬
curately because they don’t expect a supercritical com¬
puter to look at the signal.)
Let’s look at the signal. Figures 5 through 8 represent
scope patterns of data signals put on tape. In Figure 5 we
see an ideal signal with a 6 volt peak-to-peak level.
Notice the nicely squared-up data bursts with an ampli¬
tude 2 volts peak-to-peak greater than the 4-volt mini¬
mum the computer requires for reliable operation.
Figure 6 exemplifies the same signal after it passes
through a recorder with a slightly different azimuth align¬
ment from the one used for Figure 5. Note the tapered
beginnings of the top and bottom edges of the signals.
32
SYNTAX QUARTERLY/SPRING 1983
This is known as high frequency roll-off and is caused by
the inability of the recorder/ amplifier and/ or record/ play
head to reproduce the abrupt signal level change of a
square wave signal. Notice the tapered part of the signal
still exceeds 4 volts, so this amount of roll-off would not
cause data loss.
Move on to Figure 7. This illustrates a more severe
case of azimuth misalignment. The roll-off now reduces
portions of the signals below the 4-volt level. Now you
lose data and experience LOADing problems.
Figure 8 illustrates severe misalignment resulting in
almost total loss of data bursts and leaving just some
useless spiking signals which the computer ignores.
Other problems also cause poor performance of cas¬
sette machine and tapes, such as tape oxide buildup on
head gap, and poor oxide coating on tapes and noisy
recorders. These problems can be overcome rather easily.
However, if we want to build a ZX80/81 and Timex
users program exchange capability we need to “get our
heads straight” to make it work out.
ov
Nil
m
IB
dill 4 V d-d
■p
L
m
m
m
|pp__4V p p
1 6V p
- -1
Figure 8.
"IF I HAD TO CHOOSE
JUST ONE PROGRAM TO
IMPRESS AN AUDIENCE,
THEN '3D MONSTER MAZE
WOULD BE THE ONE"* ^
Price Quantity
13941 Gamestape 1: 11 Programs— IK 14.95 _
13942 Gamestape 2: 3 Games— 16K 14.95 _
13943 Gamestape 3: Catacombs Adventure— 16K 14.95 _
13944 Gamestape 4: 3D Monster Maze— 16K 14.95 _
13945 Gamestape 5: 3D Orbiter— 16K 14 95 _
PLUS BOOKS:
26025 NOT ONLY 30 PROGRAMS FOR THE ZX81 14 95 _
25957 MACHINE LANGUAGE PROGRAMMING MADE SIMPLE 19 95 _
25913 UNDERSTANDING YOUR ZX81 ROM 19 95 _
26063 ZX81 ROM DISASSEMBLY-PART A 14 95 _
26103 ZX81 ROM DISASSEMBLY-PART B 14 95 _
25895 COMPLETE BASIC COURSE FOR TS1000/ZX81 34 50 _
PLUS TAPES:
26446 SPACE TREK -16K 14 95 _
26359 SUPER INVASION-1 K 14 95 _
26318 WALL BUSTERS-1K 14 95 _
26472 10 EXCITING PROGRAMS-1K 14 95 _
26284 REVERSI— IK 14 95 _
26406 TOOLBOX-1 K 14 95 _
26490 BASIC COURSE 2 cassette pack 7 50 _
Total
$ _
3D MONSTER MAZE
Gamestape 4 Actual screen TS1000/ZX81
Orders to:
MELBOURNE HOUSE
SOFTWARE, INC.
Dept. CS
347 Reedwood Drive
Nashville, TN 37217
Signature
Total: $ _ _ Name
Residents of CA, MD, TN, please add sales taxes _ ...
S&h 2.00 Address
Enclosed is my check or money order for $ _
Please charge my Visa _ or MasterCard
Card sr _ expiration date _
Total: $_
Visa and M / C orders
can be phoned in:
615/361-3738
City _ State _ Zip _
Dealer orders and queries:
800/251-5900
(ask for a Melbourne House operator) STX
SYNTAX QUARTERLY/SPRING 1983
33
8K ROM/1 6K RAM
SOFTWARE— EDUCATION
by Dale F. Lipinski, Roslyn, PA
Make-It-
Yourself
Quiz Program
This program is a do-it-yourself quiz- writer. It lets
you choose the quiz format and tailor the questions
and answers to the student’s level. You can use Quiz over
and over for different tests.
Enter Quiz as listed. Before running the program,
SAVE it on tape. This tape is now your master copy.
Whenever you want to make new quizzes, just load your
master tape.
To use Quiz, just press RUN and ENTER (or
NEWLINE on older machines). Have your questions and
answers ready. You may use multiple choice, true-false,
or direct-entry questions. To keep students from cheating
on math problems by using the computer to calculate
answers, the program requires the student to solve math
problems before entry.
Program Explanation
Lines 10 through 300 set up the variables. Line 230
calculates how many characters the machine can devote
to your questions. The program will use almost all the
available memory. If you have more than 16K RAM and
don’t want to use it, change line 230 to:
23© LET E=©6©0- + *5)
This change will limit the program to about 16K. Line
250 displays the number of questions you requested,
then gives you the total character count for your ques¬
tions. It also tells you the average number of characters
you can use for each question. This number includes the
question, answer, choices and any explanation you wish.
Use this number as a guide to plan your entries and avoid
running out of memory.
Lines 310-760 let you input your questions, answers,
choices and any statement you want to make to the stu¬
dent about the question he/ she just answered incorrectly.
Lines 770-820 display the quiz title.
Lines 830-910 start the quiz for the student and pro¬
vide user-friendly greetings.
Lines 920-1150 are devoted to the quiz.
Lines 1160-1180 print the score. You may wish to
comment here on how well the student did.
Lines 1190-1240 give you the option of saving the
quiz program on tape. It will not retain the student’s name
or the score. If you have already saved Quiz with this
question/answer set, press ENTER to go back to the
beginning of the quiz.
Quiz is a loop program. To exit you have to BREAK
either at one of the FAUSEs or during a false SAVE
routine (you tell it to SAVE, but recorder is not turned
on) . If you accidentally BREAK and wish to continue, just
enter CONT. If that fails, enter GOTO 1160. You will be
able to restart your quiz from the beginning without losing
your questions. If you should BREAK during your ques¬
tion and answer input, try CONT. If that doesn’t work,
you’ll have to start over by entering RUN.
(Ed. Note— When you enter Quiz, follow the spacing in
the listing exactly. It is important for a nice display.
Lines with inverse video and graphics are:
Line
Graphics
. {
Inverse Video
30
32 graphic
ENTER ANSWER with
shift 7
1 space on either side
900
ZX-81 QUIZ with 1
space on either side
1020
VERY GOOD THAT
IS CORRECT with 1
space on either side
1060
I AM SORRY THAT
IS NOT CORRECT
with 1 space on either
side
1130
ENTER with 1 space
on either side
1170
CORRECT with 1
space on either side
34
SYNTAX QUARTERLY/SPRING 1983
After entering your questions and answers, you can
BREAK to stop program execution. Start your tape
recorder, then enter GOTO 1230. The program will save
to tape under the name “QUIZ.” When you next load the
tape, the program will start automatically with the quiz at
line 830. If you BREAK now and look at the program
listing, you’ll see the Z in QUIZ (line 1230) is in inverse
video. This is normal in self-starting programs.)
List of Variables Used
DIM A$(E)
DIM A (A,D)
B$
Stores all questions, answers, choices
and statements.
Used to slice DIM A$(E).
See program line 30.
Sets up the type of test.
Sets up the wrong answer explanation.
Input information.
Input information.
Explanation of wrong answer.
Quiz title.
Student name.
Used to compare correct answer to stu¬
dent’s answer.
Number of questions (length of array A).
Number of choices in multiple choice
section.
FOR-NEXT routine counter.
Depth of array A.
Length of array A$.
FOR-NEXT routine counter.
Used to calculate the length of strings.
FOR-NEXT routine counter.
Score.
SQ
An enhanced version of this program is available on C-20
tape from the author for $10. D Lipinski Software , 2737
Susquehanna Road , Roslyn, PA 19001.
5 REM "QUIZ”
10 LET S=0
2© POST _________ _ — _
^^^0CLS I »
S© PRINT “UHfiT TYPE OF QUIZ DO
YOU UISH TOHPUE?% ,*'I = HULIPLE
CHOICE" .‘*2 = TRUE OR FRL5E","3
= DIRECT hN5UER‘LB$
50 INPUT C$
T0 IF CODE C$<=28 OR CODE C$>=
32 THEN GOTO 4©
80 CL. 3
90 PRINT "HOU MR NY QUESTIONS D
O YOU UISH TO RSK7~, , 0$
100 INPUT R
110 CLS
ISO PRINT "DO YOU UISH TO EXPLh
120 PRINT "DO YOU UISH TO EXPLh
IN THE" , "HN5UER IF IT IS WRONG?"
.."I = YES",,"© = NO",,B$
130 INPUT D$
14-0 IF CODE D $ < =27 OR CODE > =
30 THEN GOTO 110
16© IF D$ = '*©‘* THEN LET H$ = " '*
17© CLS
ISO LET D=4
130 IF C$ = “2** OR C$ = **3** THEN GO
T u c38
280 PRINT "UHRT IS THE MflXIHU H
NUMBER OF** , "CHOICES PER QUESTION
7", "LIMIT OF 9**,,B!fi
210 INPUT B
215 IF B > =10 THEN GOTO 170
220 LET D=B+4
23© LET E= (PEEK 16386-PEEK 1S4-1
2+256* (PEEK 16387 —PEEK 16413J-5©
) -1300- (D* (R + l* *5)
24-0 CLS
250 PRINT "YOU WILL HRUE " ; R; **
QUESTIONS'* , "UITH R TOTRL CHRRRCT
ER INPUT OF",E;TRB 0; *’RN RUERflGE
OF ** ; E/R , "CHflRflCTERS PER QUEST I
ON";TRB 0; ** IF THIS IS OKRY ENTER
0**,'*IF NOT ENTER 1**,,B$
2S0 INPUT E$
27© IF CODE E$<=27 OR CODE E$> =
29 THEN GOTO 48
23© DIM flCR+1,0)
29© DIM R*<E*
30© LET RC 1,13=1
320 FOR F=1 TO R
330 CLS
34-0 PRINT "UHRT IS QUESTION NUM
BER F; **'?** , B$
350 INPUT E$
355 CLS
360 PRINT E$;TfiB 0; "INPUT © IF
THIS IS CORRECT" ."INPUT 1 IF NOT
CORRECT** ,B$
370 INPUT F$
330 IF CODE F$< =27 OR CODE F$ > =
29 THEN GOTO 33©
390 LET H=LEN E$
4.0Q LET RiF.2)=fi(F.l} +H
4-10 LET R$CR(F,1) tO R(F,1) +H) =
4-2© CLS
4-30 PRINT "UHRT IS THE RN5UER? '*
4.4.0 IF Ci = !!2" THEN PRINT ** I = T
RUE* . . *0 = FRLSE *'
4-5© PRINT B $
4-S© INPUT E$
465 CLS
47© PRXNT E$;TRB 0; "INPUT 0 IF
THIS IS CORRECT" , " INPUT 1 IF NOT
CORRECT** ,B$
475 IF C$ = "2" RND E$ = **l** THEN P
PINT RT 0,©; ** 1 = TRUE-
477 IF C$ = ‘*2** RND E $ = **©** THEN P
HINT RT ©,©;**© = FRLSE"
43© INPUT
49© IF CODE F $ < =27 OR CODE F$> =
29 THEN GOTO 42©
495 IF C$ = ‘‘l** THEN LET E$ = **
** -+E$
500 LET H=LEN
51© LET RCF,3) =RCF,2) +H
52© LET R$(fiiF,2) TO R(F.2) +H) =
53© IF CODE D$<=28 OR CODE D$> =
30 THEN GOTO 60©
54-8 CLS
t>t>© PHiNT " UHRT IS THE EXPLRNRT
ION** , "NO EXPLRNRT ION INPUT R 5PR
CE" . B$
560 INPUT
565 CLS
57© PRINT H$;TRB 0; “INPUT © IF
THIS IS CORRECT" ."INPUT 1 IF NOT
CORRECT" .6$
SB© INPUT F $
SO© IF CODE P$ < =27 OR CODE PS> =
22 THEN GOTO 54©
60© LET H=LEN
618 LET R CP , 4) =R (F . 3> +-H
62© LET Hf CR CF .. 3i TO K ( F , 3) +H> =
638 IF CODE C$<=28 OR CODE C-$> =
38 THEN GOTO 753
b 4 S F O H l_- = 1 T G B
558 CLS
660 PRINT 'UHRT IS THE NUMBER **
;C;*' CHOICE?" , "FOR NO CHOICE INP
UT R SPfiCE" ,B$
67S INPUT E$
Continued Next Page
SYNTAX QUARTERLY/SPRING 1983
35
F$> =
7*5©
769
7*7©
789
THE
799
795
30©
THIS
0-71^ q | _ -r.
680 PRINT C; " = l,;E$;TRB 0; “INP
UT © IF THX5 13 CORRECT", “INPUT
I XF NOT CORRECT" .B$
SO© INPUT F $
7©0 XF CODE F $ < =27 OR CODE F$ > =
29 THEN GOTO 658
705 LET E$-CHR$ (C+28) + " = "+E?fi
71© LET H=LEN E$
72© LET R (F , 4-+C) =R CF . 3+0 +H
730 LET R$ (R CF , 3+0 TO RCF.3+0
+H5 =5$
735 XF fi$(R(F.2)+l TO RCP.3) ~1)
=E$(2 TO ) THEN LET R$(RKF S2> TO
R <F .,2# ) =CHR$ CC+23)
74-© NEXT C
75© LET R(F+I,1) =RCF,Di
7S0 NEXT F
77© CLS
730 PRINT "UHRT XS THE TITLE OF
THE QUI2?",B$
79© INPUT I $
795 CLS
300 PRINT I$;TRB 0; " INPUT 0 IF
THIS 15 CORRECT"," INPUT 1 XF NOT
CORRECT" .B$
S 1© INPUT F $
320 IF CODE F$<=27 OR CODE F$ > =
29 THEN GOTO 770
83© CLS
34.0 PRINT "UHRT IS YOUR NRME PL
ER 5E?",B$
358 INPUT Ufc
3S0 CLS
87© PRINT "THRNK YOU ";U$;TRB 0
; "GET RERDY FOR YOUR QUIZ"
38© PRU5E 488
S90 CLS _ _
900 print trb 10;
; TRB 0;I$;TRB 0; "TAKEN BY ";U$
910 PRUSE 4.0©
920 FOR C=1 TO R
930 CLS
94.0 LET E$=ft$(R(C,l) TO ft*C,2>-
1)
^94.5 LET K$=R$(R«C,2) TO RCC,3) -
950 PRINT "QUESTION NUMBER ";Q.
TRB 0; E$;TRB 0; B$ i TO 32)
955 IF C$ = ‘T" THEN LET K$=R$ (R C
C.,2) TO R CC, 2) )
968 IF C$ = "i" THEN FOR 1=4. TO D
-1
978 IF C$=" 1" THEN PRINT R$ CR (C
,1) TO R CC , I + l) -1)
980 IF C$="l" THEN NEXT I
990 IF C$="2" THEN PRINT "1 = T
RUE" , , "0 = FRLSE"
1008 PRINT B$
101© INPUT F$
1030 IF K$=F$ THEN PRUSE 4-00
104-0 IF K$=F$ THEN LET 5=5 + 1
1070 PRUSE 4.0©
1030 CLS
1093 PRINT "THE CORRECT RNSUER I
5";TRB 9;R$(RiC,2) TO R(C,3)-1)
1100 IF C*="2" RND K$="l" THEN P
RINT RT 1,0; "I = TRUE"
1110 XF C$="2" RND K$="0" THEN P
RINT RT 1,0; "0 = FRLSE"
1120 PRINT R$iRiC,3) TO RiC.4) -1
)
1130 PRINT "PRESS TO CON
TINUE" <5$
114-3 INPUT E$
1150 NEXT C
1160 CLS
117© PRINT "QUIZ IS COMPLETE. TH
RNK YOU",U$;TRB 8, /‘YOUR SCORE X
S " ; s; " . "out OF r pos
SXBLE " ; R ; " QUEST IONS « " ; TRB © ; "Y
OUR GRRD5 RUERRGE IS ",5/Ril80; "
PER CENT"
1130 PRUSE 4-80
1190 PRINT RT 15,0; "DO YOU UI5H
TO 5RUE THIS PROGRRM1 = NO",,"©
= YES" , ,B$
120© LET S=©
121© INPUT F$
122© IF CODE F $ < =27 OR CODE F$ > =
29 THEN GOTO 33©
1238 SAVE 'QUIZ"
124-© GOTO 83©
SYNTRCTIC SUM: 48475, SK ROM
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36
SYNTAX QUARTERLY/SPRING 1983
Join the
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with the E-Z Keyboard . . . jKjBB SI
At last, a large 60 key “Tactile Feel”
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Hear the CLICK and feel a SNAP for every Only
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sal
E-Z Key 60 has the following features:
- 60 Keys - Legends in 3 colors on the base
- Molded legends on key tops
- 8 Automatic shift keys (no shifting required)
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E-Z Key 60 requires no wiring (just plug it in)
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SWITCH SPECIFICATIONS:
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type with arm to give .040" travel.
A custom made enclosure (shown above) is
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SYNTAX QUARTERLY/SPRING 1983
37
HARDWARE PROJECT
O""3 JL J by John Oliger, Indianapolis, IN
8K ROM/16K RAM
Build Your Own EPROM
Programmer and Centronics
Printer Interface — Part II
This is Fart II of “Build Your Own EPROM Program¬
mer and Centronics Interface.” Part I (SQ, Winter 82)
covered building the expansion board and parallel printer
port. John Oliger’s step-by-step demonstration in Part I
also included etching printed circuit boards, printer port
modification for use with full 48K RAM, decoding RAM
and testing your board. All these projects require at least
16K RAM.
The EPROM (2716) Programmer
Now we are going to build an EPROM (erasable pro¬
grammable read only memory) programmer and an
EPROM read board. The programmer will program only
the 2716 or TMS2516 EPROMs and it only programs.
You cannot verify with this board; I omitted verify cir¬
cuitry in the interests of simplicity and cost. An EPROM
programmer is not a circuit you use every day. While the
ability to verify is a nice convenience, it’s not really
necessary.
Before you can use the EPROM read board or the
EPROM programmer, you must fully decode the ROM to
keep it from conflicting with this new address space. Use
the circuit in schematic 6 on one of the spare IC sockets
on the expansion board.
If you make the 0-6K reader you will no longer need
this circuit. You should remove it to keep it from fighting
the decoders on that board.
After you program an EPROM, turn off the computer.
Remove the programmer board and take the programmed
EPROM from it. Install the EPROM in the EPROM read
board. Then load your program back into the computer
and write a small BASIC program to verify the EPROM.
When you have the printer driver on EPROM with the
original program in RAM starting at location 28672, the
verification program (listing 5) goes something like this:
Listing 5
10 LET X=81 92
20 FOR N=28672 TO 28960
30 IF PEEK XOPEEK N THEN PRIN
T X
40 LET X=X+1
50 NEXT N
Schematic 6. All
Trace Numbers
Refer to Expansion
Board Trace Num¬
bers as Already
Explained.
A15 TRACE 37B
A14 TRACE 38B
A13 TRACE 39B
GND
38
SYNTAX QUARTERLY/SPRING 1983
Our EPROM programming program (listing 6) goes like
this:
Listing 6
10
SLOW
20
LET X
= 8192
30
FOR N
= 28672
TO 28960
40
POKE
X, PEEK
N
50
LET X
= X + 1
60
PAUSE
4
70
NEXT
N
With my programmer, I’ve never had a “Not Verify1
that was the hardware’s fault. The only one I programmed
wrong was my own error. If you see dark wide horizontal
bars on the screen during programming, the EPROM is in
backwards.
The programmer has its own one-shot aboard to time
the programming pulse, so you need no software for this.
But be careful not to address this block of memory again
for at least 50 ms. Hence the PAUSE 4 in line 60. Don’t
leave this line out!
To build the programmer, etch and plate the board just
like the port board you already built. Use board layout 3.
On this board you need to jumper from pin 10 of U5 to
ground on the bottom. When installing the feedthroughs,
be careful not to put any where C6, C5, Cl and R1
mount (just to the left of U3) . They are soldered top and
bottom, so their leads act like the feedthrough (see
schematic 7).
Solder a solid red wire to the bottom of the board to
pad marked Vpp. Solder a solid black wire to pad 12 of
the 2716 (ground). These wires should extend about 2
inches above the top of the board. Strip the ends and
bend them into an O shape. You will connect the 25 volt
supply to these when you program.
The 25 Vdc regulated power supply necessary to pro¬
gram should have a tolerance of + or - 1 volt. You may
use any well filtered and regulated supply you like, or you
can construct the circuit in schematic 8 on a small perfo¬
rated board. It draws very little current, so use the
smallest and cheapest transformer you can find.
Turn on the supply just before you run the BASIC pro¬
gram, and turn it off as soon as programming is complete.
It should be off while you enter the driver program and
while you turn the computer on and off. Without this
voltage present, no programming can take place. Use
alligator clips on the output wires from your supply to
connect it to the solid wires on the board. Be careful to
keep them from touching any other boards or parts. Also
be careful not to attach them backwards! Use a red alli¬
gator clip for -1-25 and a black one for ground.
Don’t forget to install C2 and C3 on the bottom of the
board. All vertical ICs have pin 1 down, while horizontally
mounted ICs (U4 and U5) have pin 1 to the left (viewing
from component side of board). Because you probably
won’t program EPROMs for a living, a ZIF (zero insertion
force) socket for the EPROM is not necessary. Be sure to
use only quality parts for R1 and Cl. I used a “mono¬
lithic” capacitor for Cl (5%). Use a resistor measured to
be very close to 450K.
EPROM Read Boards
After you have the printer converter/driver routine in
EPROM, you need to make the 8-16K EPROM read
SYNTAX QUARTERLY/SPRING 1983
39
board. Use the same method we used for all the other
boards in these projects, using board layout 4. The socket
on the bottom is mapped 8192-10239. Second from the
bottom is mapped 10240-12287. Third from the bottom
is 12288-14335. The top one is mapped 14336-16383.
After you build the 8-16K read board, you can burn
the printer driver into ROM (listings 9 and 10) . Then after
you build the 0-6K board, you can use LFRINT, LLIST
and COPY to your printer port!
Don’t forget to install the wire jumper from pin 1 U1 to
pin 6 U2. The tantalum bypass capacitor, C3, should be
mounted underneath the bottom EPROM socket. This is
because Vcc and ground come into the memory array
from the top and are, of necessity, small. The exact value
is not critical because it is only really used as a “storage
tank.” Again, Vcc and ground should be built up with
solder for low impedance. Cl is mounted just above Ul;
C2 is mounted just left of E4. Be sure to observe polarity
on these components (see schematic 9) . If installed back¬
wards, they will sometimes blow up like a firecracker!
Our final project is to construct the 0-6K EPROM read
board. On it you will mount one to three EPROMs con¬
taining the monitor with a few changes. Construct the
0-6K board just like you are building another 8-16K
board, except make the changes listed on the schematic.
You will not use the top socket on this board (see sche¬
matic 10).
We want at least part of the monitor on EPROM so we
can change things. The main changes we want are in the
second 2K block (E2 — 2048-4095), specifically, a call to
02E7 at 0876H. After this patch, we can use all Sinclair’s
printer commands, LLIST, LPRINT, and COPY. At this
point in the ROM, the HL register points at the first char¬
acter to print and the D register contains the number of
lines to print (1 if printing from the printer buffer or 22 if
printing from the display) . We want to change this call to
40
SYNTAX QUARTERLY/SPRING 1983
MAPPED FROM 8192 TO 10,239 DECIMAL
2000 TO 27FF HEX
Ins . TMS-2516 or
Non-Texas Ins. 2716
EPROM Program¬
mer
SYNTAX QUARTERLY/SPRING 1983
41
02E7 to a call to 20C8. With the call to 20C8, the com¬
puter goes to our ASCII convert/ drive routine instead of
entering the temporary FAST mode as originally in¬
tended. Here we save on the stack the registers we will
use, convert the characters to ASCII and send them to
the printer, get the registers back that we saved, and then
simply jump to 02E7 for the monitor. If the ZX printer is
attached, it will print the same thing our printer just did. If
our printer’s own print switch is off, the computer just
prints to the ZX printer.
To change 0877 from E7 to C8 and 0878 from 02 to
20, copy this part of the ROM to EPROM with the BASIC
program in listing 7 and, of course, our EPROM
programmer.
The next program, listing 8, copies the first block of the
monitor. In it, we change location 4 from FFH to FEH
and location 5 from 7FH to FFH. With this change, the
monitor checks all our memory on power up, rather than
just 16K. Now if you have greater than 16K on your com¬
puter, you won’t have to move RAMTOP every time you
power up.
You change location 3 to only 254 because the monitor
increments the initial value and stores it as RAMTOP.
Thus it would increment 255 to 0 and store 0 as RAM-
TOP. The system would still function, but the display file
Listing 7.
1 0
SLOW
20
LET X=81 92
30
FOR N=2048 TO
2166
40
POKE X , PEE K N
4 . t
50
LET X=X+1
*
60
PAUSE 4
70
NEXT N
80
PAUSE 4
90
LET X=X+2
100
FOR N=21 69 TO
4095
1 1 0
POKE X , P E E K N
120
LET X=X+1
130
PAUSE 4
140
NEXT N
150
POKE 8311,200
160
PAUSE 5
170
POKE 8312,32
42
SYNTAX QUARTERLY/SPRING 1983
Listing 8.
1 0
POKE 8192,
PEEK
20
PAUSE 5
30
POKE 8193,
PEEK
40
PAUSE 5
50
POKE 8194,
PEEK
60
PAUSE 5
70
POKE 8195,
254
80
PAUSE 5
90
POKE 8196,
255
100
PAUSE 5
1 1 0
LET X=81 97
120
FOR N=5 TO
2047
130
POKE X , P E E
K N
140
LET X=X+1
150
PAUSE 4
160
NEXT N
would be collapsed. Then the more memory your pro¬
gram used, the longer the computer would take to print
something on the screen. I know, because I changed
location 3 to 255 the first time!
You can program the third block without any changes.
However, now that it is on EPROM, you could change it
if the need arose. The last block can be programmed
directly also if you want to put it on EPROM. If you do,
you have to mount it inside the computer and slightly
rewire the socket (see below). Because the character
generator is in this last block of memory, you may want to
put it on EPROM to change the characters. I changed the
British pound sign to a “!” because I didn’t use the pound
sign enough to justify its own key.
If you choose to only put the second block on EPROM,
then you must also build the little circuit to decode for this
(see schematic 1 1) .
ASCII Convert and Copy Routine
Multilength Character Lines. (POKE system flag 16507
the number of ‘ENTERs’ to ignore. 16508 is used as a
counter.) (Listing 9.)
ASCII Conversion Table
2000
20
81
82
83
94
95
96
97
2008
FF
FC
83
22
21
24
3A
3F
2010
28
29
3E
3C
3D
2B
2D
2A
2018
2F
3B
2C
2E
30
31
32
33
2020
34
35
36
37
38
39
41
42
2028
43
44
45
46
47
48
49
4A
2030
4B
4C
4D
4E
4F
50
51
52
2038
53
54
55
56
57
58
.59
5A
2040
20
20
20
20
20
20
20
20
2048
20
20
20
20
20
20
20
20
2050
20
20
20
20
20
20
20
20
2058
20
20
20
20
20
20
20
20
2060
20
20
20
20
20
20
20
20
2068
20
20
20
20
20
20
20
20
2070
20
20
20
20
20
20
0D
20
2078
20
20
20
20
20
20
20
20
2080
FF
FE
FD
FC
EB
EA
E9
E8
2088
FF
83
FC
40
23
24
7E
25
2090
7B
7D
3E
3C
26
2B
5F
2A
2098
2F
60
27
2E
30
31
32
33
20A0
34
35
36
37
38
39
61
62
20A8
63
64
65
66
67
68
69
6A
20B0
6B
6C
6D
6E
6F
70
71
72
20B8
73
74
75
76
77
78
79
7A
If you wish to put the last block (6-8K) on EPROM, cut
the foil trace from pin 18 of the ROM socket and jumper
pin 18 to ground (pin 12) . Then cut the trace to pin 21 on
the ROM socket and jumper pin 21 to Vcc (pin 24). The
6-8K EPROM must be in the main computer because it
contains the character generator. Install the programmed
2716 into the ROM socket exactly as the original ROM
was installed. SQ
SYNTAX QUARTERLY/SPRING 1983
43
Listing 10
Address
Location
Contents
20C0
1616
20C2
2A0C40
20C5
23
20C6
1811
Calls here (20C8) from monitor
20C8
3AFFFF
20CB
CB5F
20CD
2807
20CF
E5
20D0
D5
20D1
CDD920
20D4
D1
20D5
El
20D6
C3E702
20D9
7E
20DA
23
20DB
E5
20DC
210020
20DF
85
20E0
6F
20E1
3001
20E3
24
20E4
CD460F
20E7
3808
20E9
3E0D
20EB
32FFFF
20EE
El
20EF
CF
20F0
oc
Label
Mnemonic
COPY
LD D,16
LD HL,(DFILE)
INC HL
JR CONV
PTCH
LD A, (PORT)
BIT 3, A
JR Z RETP
PUSH HL
PUSH DE
CALL CONV
POP DE
POP HL
RETP
JP TFAS
CONV
LD A,(HL)
INC HL
PUSH HL
LD HL.TABL
ADD L
LD L,A
JR NC BRK?
INC H
BRK?
CALL 0F46
JR C CHEK
LD A,0D
LD (PORT), A
POP HL
RST 08H
REPORT D
Comment
;Set ‘D’ for 22 lines
;Get screen memory address
; Point at first
character
;Go and copy the
; screen
;Get printer status
;Is print switch on?
; Return to monitor
; if not save registers
;used for ZX printer
;use, later
;Call ASCII Conv/Drive
; Routine
; Restore registers
;for ZX printer use
;Jump to Temp Fast’
;for monitor
;Get character code to
;LPRINT
; Point at next
character
;Save location for
; later
; table
;Point at conversion
; table
;Add displacement code
;Put this in “lo” byte
;Jump over inc if no
; carry
; Increment “hi” byte
; Check for depressed
; break key
; Jump over return if
;no break
;Put ASCII code for
; carriage return in A
;And send it to the
; printer
; Clear next address
;from stack
; Return w/report UD”
; Break key pressed
44
SYNTAX QUARTERLY/SPRING 1983
Listing 10 Continued
Address
Location
Contents
Label
20F1
1E02
CHEK
20F3
3AFFFF
RDY?
20F6
FE18
20F8
20EA
20FA
ID
20FB
20F6
20FD
7E
GUT
20FE
FEOD
2100
2012
2102
217B40
LDN?
2105
F5
2106
7E
2107
23
2108
BE
2109
2805
210B
FI
210C
34
210D
15
210E
1807
2110
FI
CCNT
2111
3600
2113
15
2114
32FFFF
SEND
2117
El
2118
20BF
211A
C9
Mnemonic
Comment
LD E,02
;Set ‘E’ to check
; status twice
LD A, (PORT)
;Get printer status
CP 18
;Is it ready to
; receive?
JR NZ BRK?
;Loop to break test if
;not
DEC E
; Decrement check
; counter
;o.k.
JR NZ RDY?
;Loop ‘till 2 times
LD A,(HL)
;Get converted code to
;send
CP 0D
;Is it an “ENTER”?
JR NZ SEND
;Go and send it if not
LD HL,FLAG
; Point at multiline
;flag
PUSH AF
;Save “ENTER” on the
; stack
LD A,(HL)
;Now, get the flag
INC HL
; Point at the counter
CP (HL)
; Ready to send “ENTER
;now?
JR Z CONT
; Clear counter & send
; enter if true
POP AF
; Clear the stack
INC (HL)
; Increment counter
DEC D
; Decrement line
; counter
JR 2117
;Jump over driver,
; this time
POP AF
t
;Get “ENTER” to send
LD (HL),00
; Reset the counter
DEC D
; Decrement the line
; counter
LD (PORT), A
;Send character to the
; printer
POP HL
;Get next char address
;to convert
JR NZ CONV
;Go do next char if not
;done
RET
; Return to caller
SYNTAX QUARTERLY/SPRING 1983
45
Operation Codes
of the 8080, 8085,
and Z80 Processors
D Martin Harrell
313 Hollyberry Rd
Se verna Park MD 21146
Manual conversion between assem¬
bly language mnemonics and hexa¬
decimal object code can be tedious —
particularly if much code is involved.
However, the task does not have to
be overwhelming. A conversion table
helps immensely and is also a good
training aid for novice programmers.
It presents the entire instruction set in
compact form, revealing useful pat¬
terns, and also inconsistencies.
8080 and 8085 Operation Codes
Operation codes for the Intel 8080
and 8085 microprocessors are shown
in table 1. The only difference be¬
tween the instruction sets for this pair
is that the 8085 has two additional in¬
structions: the read-interrupt-mask
instruction (mnemonic RIM, hexa¬
decimal code 20), and the set-inter¬
rupt-mask instruction (mnemonic
SIM, hexadecimal code 30). They
allow the user to control interrupts
and a serial I/O (input/ output) line,
thus making them useful additions.
The position of an 8080/8085 oper¬
ation code in the table does not give a
reliable clue about the implied ad¬
dressing mode. Table 1 is generally
organized according to the operands
involved. Residing in the middle eight
columns of the table (columns 4 thru
B) for example, are the instructions
for single-byte move, arithmetic, and
logical operations. (Length attributes
in this article refer to data, rather
than instruction length, unless other¬
wise noted.) Regardless of the
column, progression through the
eight possible choices for the source
(second) operand is always in the
same sequence as the user moves
down a column: registers B thru L;
followed by memory reference; and
finally, register A, the accumulator.
Then, because each column has six¬
teen entries, the sequence repeats. If
the arithmetic and logical instruction
groups do not seem to conform to this
rule, note that the first operand
(always register A) is implied rather
than stated explicitly.
This same sequence is used for ad¬
vancing through choices for the
destination (first) operand. In this
case, however, progression is column
to column from left to right, with
each successive column containing
two of the eight possible operands.
The double-byte instructions also
conform to this first-operand type of
arrangement. Most of these appear in
the first four columns of the table;
however, the stack commands to
PUSH and POP double-byte data are
located at the far right in the top
section.
An apparent inconsistency appears
in the middle of the table. Hexa¬
decimal code 76 is the instruction to
halt the processor (HLT). Expected
there instead is MOV M,M, the op
code meaning "move the content of
the memory location whose address is
in the H and L register pair into that
same memory location/' The expect¬
ed instruction is effectively just a slow
equivalent of the no operation (NOP)
located at hexadecimal 00. Hence, its
replacement by the halt command
improves, rather than degrades the
power of the instruction set. Still, I
wonder why an otherwise empty spot
in the table was not chosen — as was
done for the two additional 8085
instructions.
The right quarter of the table main¬
ly contains program branching and
data exchange instructions. Excluding
the previously mentioned stack com¬
mands, none of these have explicit
operands so the previously discussed
organization is impossible. The mis¬
cellaneous nature of these instruc¬
tions also tends to prevent predictable
order.
Nonetheless, the op codes in this
area have a consistent structural
style. Most are arranged in com¬
plementary order, with mutually
exclusive conditions placed in the
same column, separated by eight
rows. The group of return instruc¬
tions is typical. The unconditional
return from subroutine command is
hexadecimal C9. Starting immediate¬
ly above it and proceeding to the
right, four of the eight conditional
return instructions are found. The
other four (the complements) are
eight rows higher.
The order in which these condi¬
tions appear is uniform from group to
group. To determine that this is so,
compare similar elements of the call,
jump, and return groups. The uncon¬
ditional jump (JMP) instruction is a
curious exception. Its expected code is
CB, but it actually appears eight rows
higher in the table. Such exceptions
are few enough not to be bothersome.
Z80 Operation Codes
The Z80 is an enhanced version of
the 8080. It runs faster, has twice as
many general purpose registers, and
has a much larger instruction set.
Included as a subset in this instruction
is the entire repertoire of the 8080.
(This compatibility exists at the
“From Operation Codes for 8080, 8085, and Z80 Processors by D. Martin Harrell
appearing in March 1980 issue of BYTE magazine. Copyright ©1980 Byte Publica¬
tions, Inc. Used with the permission of Byte Publications, Inc.”
46
SYNTAX QUARTERLY/SPRING 1983
machine language level, but not the
assembly language level; standard
mnemonics and assembly language
formats tor the two processors differ
considerably.) Thus, in hexadecimal
object form, almost any program
written for the 8080 will produce
identical results when executed by a
Z80. Because of the Z80's generally
higher speed, software timing loops
are an exception to this upward com¬
patibility feature. [Editor's note:
There is also a slight difference in the
operation of the parity flag . . . .RSS]
The similarities of the two instruc¬
tion sets can be seen by comparing
corresponding positions of table 1
and table 2. Table 2 is the basic con¬
version table for the Z80. For every
valid 8080 instruction in table 1, its
correspondent in table 2 produces
logically equivalent results. The dif¬
ferences between the two instruction
sets stem from the twelve positions
unused by the 8080. These, which are
clearly indicated in table 2, are used
to greatly expand the Z80's capabil¬
ity.
The Zilog Corp used the seven un¬
filled positions on the left side of table
1 and the uppermost one on the right
side to give the Z80 processor the
ability to perform relative branching
and to exchange the contents of its
two sets of registers. However, the
use of hexadecimal codes 20 and 30
for two of the jump relative instruc¬
tions means that the Z80 is not as
compatible with the 8085 as it is with
the 8080.
The real expansion of the Z80's in¬
struction set over that of the 8080 is
the result of the interesting use of the
four other empty spaces in table 1. In
essence, the Z80 uses them as pointers
to four additional 16 by 16 tables,
thus increasing the number of possi¬
ble op codes by 1532. (The Z80 does
not use most of these, but flexibility
for future expansion is certainly
there.) Had this innovative use of the
unimplemented codes not been done,
the Z80 would have been limited to
256 different op codes, which is only
twelve more than the 8080.
There is a penalty for this flexibi¬
lity: all instructions in these expan¬
sion sets must be multibyte. The first
byte identifies the appropriate expan¬
sion instruction set, after which, the
second byte identifies the operation
to be performed. Sometimes there is
an additional third or fourth byte to
provide data or addressing informa¬
tion.
Shift, Rotate, and Bit
Manipulation Instructions
Consider these pointer instructions
one at a time. All of the instructions
which begin with hexadecimal CB are
contained in table 3. All of the direct¬
mode instructions to shift or rotate
(in either direction) any byte in
memory or in any of the eight active
registers are located here. Table 3 also
contains the direct-mode instructions
to set, reset, or test any bit in any of
these bytes. All of these operations
have a length of two bytes. Interest¬
ingly, there are more valid instruction
combinations derived from the ten
basic instructions in this table than
there are in the entire 8080 set.
Two features of table 3 are notable.
The first is the absence of a 'shift left
logical" counterpart to the SRL com¬
mand group. The shift left logical
counterpart is not there because it is
not needed; the "arithmetic shift left"
instructions in column 2 (hexa¬
decimal) accomplish this function.
The use of the same general organi¬
zational rules indicated earlier for the
8080 is the more important of the
two properties of this table. Such
uniformity is a good aid in locating
instructions in this table.
Indexed Instructions
Instructions beginning with hexa¬
decimal DD are in one of two indexed
classes of instructions. These use the
IX and IY registers respectively in
forming a data address. Those related
to the former are depicted in table 4
and its associated table 5.
The analogy between tables 2 and 4
and between tables 3 and 5 is striking.
The organizational patterns are iden¬
tical — even to the point of using the
same expansion technique. They
should be identical. Each of these
indexed instructions was formed by
replacing the (HL) operand of an
equivalent register-indirect instruc¬
tion with the indexed notation
(IX + d). Thus, every operation that
can be performed in the register-
indirect mode by the 8080 or Z80 can
also be performed in the indexed
mode by the Z80.
The resulting positional equiva¬
lence between the two sets of tables is
most helpful in determining the
required hexadecimal code for the
indexed instructions. An easy way to
do this without having to refer to
tables 4 or 5 is to first select from
table 2 or 3 (as appropriate) the hexa¬
decimal code for the register-indirect
form of the desired operation. Then
place a DD prefix in front of this code
if the operation was found in table 2,
or a DDCB prefix, if found in table 3.
Finally, place after this code group a
displacement suffix, d.
The Z80 also has a second index
register, which is designated the IY
register. Op codes which use it for
addressing are contained in tables 6
and 7. It takes only a quick glance to
notice the strong similarity between
tables 4 and 6 and between tables 5
and 7. As might be expected, virtual¬
ly everything said previously about
the IX class of op codes also refers to
the IY class. The sole exception to this
statement is that the IY-type instruc¬
tions begin with hexadecimal code
FD, instead of DD.
Miscellaneous Additions
All fifty-six instructions in the last
of the four expansion sets begin with
hexadecimal code ED. They are listed
in table 8. Though they are quite
heterogeneous, they add considerably
to the power of the Z80. Among
these, for example, are instructions
that enhance the 16 -bit arithmetic
capability, set interrupt modes, per¬
mit complementing the accumulator,
and allow a register-indirect type of
I/O to be performed. There are
instructions also, which allow coun¬
ting or block processing to be done
during loading, comparison, and I/O
operations. Even if the other three
expansion sets were omitted, the
instructions in this set would be
highly useful additions to the basic
8080 complement.
With such a hodgepodge of func¬
tion, it is rather surprising that any
order at all can be made of these ED
class instructions. Nonetheless, con¬
sistency with the other tables is main¬
tained. It is evident from the arith¬
metic and the leftmost I/O instruc-
SYNTAX QUARTERLY/SPRING 1983
47
tions that arrangement by order of
tirst and second operands is used
whenever possible. Separation of
complementary functions by eight
rows in a column is also followed.
There are 696 valid op codes in the
seven Z 80 tables. Without organiza¬
tional consistency, conversion of
these instructions from mnemonic to
hexadecimal form would be extreme¬
ly difficult and probably ridden with
error. Fortunately, these codes are
very well arranged, following the pat¬
tern established for the 8080. It takes
a little practice to become adept at
making these transformations, but
with the aid of these tables it can be
accomplished successfully. ■
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48
SYNTAX QUARTERLY/SPRING 1983
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M
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PUSH AF
OR n
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a
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JP M,nn
M
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CP n
X
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Cd
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EX (SP),HL
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PUSH HL
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RST 20H
RET PE
JP (HL)
JP PE,nn
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XOR n
RST 28H
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OUT (n),A
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SUB n
RST 10H
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X
X
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IN A, (n)
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SBC A ,n
RST 18H
o
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CALL nn
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RST 08H
X
OR B
OR C
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OR E
X
X
o
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OR (HL)
OR A
CP B
CP C
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CP A
X
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AND H
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AND (HL)
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SUB L
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SBC A ,B
SBC A,C
SBC A,D
SBC A,E
SBC A,H
SBC A ,L
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00
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ADD A,C
ADD A,D
ADD A,E
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ADC A,D
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LD (HL),C
X
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LD (HL),H
LD (HL),L
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LD (HL) , A
LD A,B
—
LD A,C
X
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9
LD A,E
X
3
LD A, L
LD A, (HL)
LD A, A
SO
LD H.B
LD H,C
X
X
3
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X
3
X
X
3
LD H,L
LD H,(HL)
LD H,A
LD L,B
LD L,C
LD L,D
LD L,E
LD L,H
LD L,L
LD L,(HL)
X
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3
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3
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X
1
c
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3
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JR NZ,e
LD HL,nn
LD (nn) ,HL
INC HL
INC H
DEC H
LD H,n
1
CD
ini'
CC
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LD HL, (nn)
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DEC L
c
X
3
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a
9
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INC DE
INC D
DEC D
c
pq
3
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1
X
3
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INC E
DEC E
fi
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3
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§
a
3
LD (BC) , A
INC BC
INC B
DEC B
LD B,n
RLCA
u.
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X
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DEC C
LD C,n
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SYNTAX QUARTERLY/SPRING 1983
49
Table 2: Mnemonics of the operation codes of the Z80 microprocessor arranged for conversion to hexadecimal object code. Corre¬
sponding positions of table 1 and table 2 generally perform the identical function, despite differences in notation. Enhancements of
the 8080 instruction set are indicated by shading. Mnemonics used here are those specified by Zilog.
First Nybble
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50
SYNTAX QUARTERLY/SPRING 1983
Table 4: Operations of the Z80 invoked by the instruction prefix DD. These provide indexed-mode instructions equivalent to the
indirect-mode instructions and employ the IX register.
(ix+d) RL (ix+d) SLA (ix+d) BIT 0,(lX+d) BIT 2,(lX+d) BIT 4,(lX+d) BIT 6,(lX+d) RES 0,(lX+d) RES 2,(lX+d) RES 4,(lX+d) RES 6,(lX+d) SET 0,(lX+d) SET 2,(lX+d) SET 4,(lX+d) SET 6,(lX+d)
B
SYNTAX QUARTERLY/SPRING
Table 6: Indexed instructions employing the IY register. Note the similarity with table 4. These operation codes begin with the FD prefix.
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TIMEX/SINCLAIR 1 OOO DISPLAY
"TO FULL COLOUR GRAPHICS
K 0 L or w onus
LOOK AX THE FEATURES
Plugs into ZX81/1000 (edge connector)
Latest technology with TMS9918 VDP
(32 sprite levels)
Module contains it's own memory
All text will run on the color tv
I i
User defined characters & graphics up to
256x192 pixels
Module contains extension of basic
commands including: PAPER/INK/
BORDE R/BIN/SP RITE/OUT/IN P/etc
-For- 95
KOLORWORKS COMES WITH A LIMITED WARRANTY ON PARTS AND WORKMANSHIP
USE YOUR KOLORWORKS IMMEDIA TEL Y WITH A GAME CASSETTE FOR $9.95
This delightful game is designed for hours of fun using some of the color graphic capabilities of
KOLORWORKS. The cassette also contains a short program to familiarize you with some of the
commands and graphics.
)□□□□□□□□□□□□□□□□□□□□□□□□
Enjoy Game Fun With
GAAMWORKS
THE SOON TO BE RELEASED GAME MODULE
(proto type stage) WILL OFFER SOUND, ROM
CARTRIDGES AND JOY STICK PORTS FOR
YOUR TS1000/ZX81.
♦ THE SOUND will be of arcade game quality
which you can program for music, animals, trans¬
portation (auto, train, airplane, etc.) and ma¬
chine sounds.
♦ ROM CARTRIDGES will have up to 8K of ROM
using either 2716, 2732 or 2764 EPROMS. We
will have pre-programed cartridges and blank
cartridges which you can program. We will be
offering a service to burn EPROMS from your
cassettes.
♦ JOY STICK PORTS will allow for the use of two "Atari''®compatible joy sticks.
SORRY PRICE IS NOT AVAILABLE AT THIS TIME! GAAMWORKS WILL BE AVAILABLE BY MAIL ORDER
STARTING MARCH 1st. FOR FURTHER INFORMATION , SEND $2.00 (Credited to Order).
_ At this time KOLORWORKS and GAAMWORKS is available only by mail order.
MAIL TO: BRAINCHILD COMPUTER WORKS, INC.
P.O. Box 506
Pewaukee, Wl 53072
PRICE QTY. AMOUNT
KOLORWORKS
$149.95
CASSETTE
9.95
Shipping & Handling
4.95
4.95
Wi. residents add sales tax TAX
TOTAL
My Qcheck Q money order is enclosed ENCLOSED
Name
Street
City
State
Zip
52
Please allow six to eight weeks for processing. Thank you.
SYNTAX QUARTERLY/SPRING 1983
RES 4,(lY+d) RES 6,(lY+d) SET 0,(lY+d) SET 2, (IY+d) I SET 4, (iY+d) I SET 6,(lY+d)
SYNTAX
Table 8: The class of miscellaneous instructions invoked by the ED prefix.
SOFTWARE REVIEW
Sky-High ZX/TS
Name: Flight Simulation
Type: Game/Education
ROM/RAM reqd: 8K/16K
Listable? Yes
Printed listing? No
Screen prompts? Yes
Easy to load? Yes
Display: Excellent
From: Sinclair Research Ltd.
3 Sinclair Plaza
Nashua, NH 03061
Price: $9.95
Psion’s Flight Simulation comes on
tape with a seven-page instruction
leaflet that fits inside the cassette
case. The detailed instructions pro¬
vide a good introduction to flying
novices. After a short time, you’ll
have no trouble remembering what
keys control which aircraft functions.
Instead, you can concentrate on fly¬
ing and landing safely.
My tape consistently loads for me
every time 1 use it. The “flip” side is
blank. The program is listable and in¬
cludes a good bit of machine code.
Flight Simulation sets up two situa¬
tions. You may choose just the final
approach or “full feature.” The final
approach situation lines you up
nicely on the correct vector about
five miles out, 800 feet in the air. Full
feature sets you randomly within 25
miles of the airport. You must pilot
yourself to the correct vector and
altitude for your final approach. It is
not as easy as it sounds, especially if
you allow the wind to be a factor.
You get three different screen
displays — cockpit, map or moving
runway.
On the cockpit display, you see
the pilot’s view of the instruments
and a silhouette of the horizon as
seen from inside the aircraft. Given
the ZX/TS graphics, it is a very effec¬
tive, functional display.
For a map of the entire area
around the airport, use the map
display. The map extends about 20
to 25 miles from the landing field.
Shown on the map are the landing
field, the six beacons you can use for
guidance, some cliffs east of the
landing strip, and your heading. A
flashing dot on the map represents
your current position. This very nice
display is remarkably detailed.
Display three is a moving display
of the runway as you approach for
landing. Yes, it does move. It also
shows your speed and altitude. This
display is extremely well done and
impressive to see.
You may crash your craft in a
variety of ways, with a nice graphic
explosion and subsequent crash
report telling you what happened.
You may tear off your wing flaps,
land with your landing gear up,
smack into the escarpment at too low
an altitude, go into irreversible dives,
and more (all of which I’ve done) .
This is the most impressive game
program I’ve seen for the ZX/TS. It’s
definitely not a make-do-with-
what-I’ve-got program. Rather, it
uses the ZX/TS capabilities well to
turn out an excellent simulation. This
program is a terrific bargain at $9.95.
Thanks to Psion for making Flight
Simulation, and to Sinclair for pro¬
viding it in the US.
Michael Roberts
Des Moines, IA
New Calc
Name: VU-CALC
Type: Business/Financial
ROM/RAM required: 8K/16K
(ZX81 or
TS1000 only)
From: Sinclair Research Ltd.
3 Sinclair Plaza
Nashua, NH 03061
or
Stanhope Road
Camberley, Surrey
England GU15 3PS
Written by: Psion Software
Price: $14.95 or £7.95
VU-CALC is a program to cal¬
culate and display tables of numbers
and names. The basic table consists
of a grid— 26 rows labelled A to Z
and 36 columns labelled 01 to 36.
The grid size is fixed, so you must
load and save the entire grid,
whether you need it or not.
Loading a VU-CALC tape with no
data takes about two and a half min¬
utes. Once you enter even one num¬
ber, the program dimensions the
grid. To save and load a program
containing any amount of data takes
six minutes.
This grid is displayed in segments of
nine rows and three columns (see Fig¬
ure 1). Fortunately, scrolling is rapid
so you can access any grid position
quickly. VU-CALC treats titles as data
and scrolls them off the screen. But
you quickly get used to this and learn
to equate grid designations with titles.
For each grid position you want
the computer to calculate, you must
provide a formula. A formula con¬
sists of grid designations, constants if
necessary, and any of the arithmetic
operators + (add), - (subtract), *
(multiply) and / (divide). E$ch for¬
mula can contain a maximum of 32
characters. Since each grid designa¬
tion requires three characters, you
can add together a maximum of
eight rows or columns, for example,
A02 + B02 + C02 4- D02 + E02 +
F02 + G02 -I- H02. Fortunately you
don’t need to type this lengthy for¬
mula at each grid position you need
to compute. VU-CALC can repeat a
formula along a row or column. It
can be repeated absolutely (exactly
as entered) or relatively (with the grid
designations incremented appropri¬
ately) . Sinclair’s instruction sheet
states simply, “You may use up to 40
54
SYNTAX QUARTERLY/SPRING 1983
^[SISOFTWARE REVIEW
formulae” and here is where a serious
program deficiency arises.
I first interpreted this statement to
mean you can only calculate 40 grid
positions, but this proved incorrect.
Apparently it means you can enter
40 different formulae. A formula
repeated 36 times along a row
counts as only one formula.
Although you can delete a formula
from a given grid position, you can
never delete a formula from the
subroutine that checks for the
40-formula limit. This means you will
Magic on Tape
Name: Programmers’ Toolkit;
Graphics Toolkit
Type: Utility
ROM/RAM reqd: 8K/16K
Written in: Machine code
Listable? No
Printed listing? No
Easy to load? Yes
From: Softsync Inc.
14 E. 34th St.
New York, NY 10016
212/685-2080
Price: $14.95 each, 2/$25 mail
order only
Programmers’ and Graphics
Toolkits are two separate utility
packages. Together they form a
dynamite package to help you write
professional-looking programs for
your ZX/TS computer.
eventually reach an unrecoverable
error condition where you can enter
no more formulae. You can get there
very quickly if you use formulae to
enter data into your table. You can¬
not know how many formulae you
have entered (short of counting), so
the error comes without warning. I
have written to Sinclair asking how to
recover from this error, but they have
not yet answered.
Numbers entered in the grid are
aligned along the left side, not along
the decimal point. You can enter up
These toolkits let you store
machine code routines in your com¬
puter to perform often-used tasks or
tricks neatly and quickly. You load
each in the usual way (one requires
an initial POKE). They move
themselves above RAMTOP, the
place the computer thinks is the end
of memory. Then you can enter or
load other BASIC programs as if the
machine code routines were not
even there. The machine code pro¬
grams are protected against being
overwritten by BASIC programs. But
whenever you need a toolkit routine,
just enter the appropriate USR call
and it executes.
You can use each toolkit sepa¬
rately or both together; they are
compatible. Each comes with cards
giving loading tips, directions, com¬
mand summaries, and examples for
you to try out. Be careful when
to eight numbers in each grid posi¬
tion. Calculation attempted on a grid
containing an alphabetic character or
an empty grid position produces a
C/5110 error. Load empty grid posi¬
tions with zeros if you wish tp include
them in calculations.
Instructions supplied by Sinclair
consist of seven sheets sized to fit in
the tape box. Rather than teach you
how to use the program, they give
you just enough information to let
you experiment and teach yourself.
VU-CALC is written in machine
code and runs adequately fast except
when you enter formulae or data.
You must pause between each key¬
stroke when entering data to keep it
from getting lost. Possibly this delay
is not noticeable with the standard
ZX/TS keyboard, but anyone with a
typewriter-style keyboard will cer¬
tainly notice it. A numeric keypad
would be useless for entering data
due to the program’s slow response.
Although VU-CALC has several
shortcomings, it is a very useful tool
for anyone who has to work with
tables of numbers. If Sinclair or Psion
can resolve the “over 40 formulae”
error condition, I will give VU-CALC
a high recommendation.
D.V. Carville
APO New York
following the directions. I found
three errors in the instructions for the
first graphics routine. They are sim¬
ple to find and fix; two are left-out
greater than and less than signs, the
third is an extra character/ in a line
number (105 should be 15).
One particularly good feature is
the Graphics Toolkit’s error mes¬
sages. If you make a mistake using a
routine you aren’t likely to crash the
machine. Instead you get a report
code akin to the computer’s own,
telling you the error and the line
number it occurred in. Toolkit error
codes use letters G to S, so they
don’t coincide with the computer’s
own error codes.
Programmers’ Toolkit offers these
routines: line renumbering (also re¬
numbers GOTOs and GOSUBs),
search and replace, search and list,
hypergraphics mode (alters the
SYNTAX QUARTERLY/SPRING 1983
55
^ g SOFTWARE REVIEW
starting address of the character set) ,
screen fill, reverse video, wait (pro¬
grams holds until the computer re¬
ceives input from the tape recorder)
and bytes free.
Graphics Toolkit offers 23 routines
in all: draw/undraw (define your own
shapes), .foreground on/off, border/
unborder, screen fill, reverse video,
up/down/left/right (alter next
PRINT position), editprint (changes
current PRINT position to screen line
23), upscroll, downscroll, rightscroll,
leftscroll, onscreen/offscreen (turns
screen display on and off), back¬
ground on/off, search and replace,
and square (draws a square or rec¬
tangle to specified coordinates).
Each program requires a 16K
RAM pack because of the RAMTOP
adjustment. Using the two toolkits
together, you still have about 13. 5K
of memory available.
With the USR calls to the machine
code routines, you effectively add 32
commands to the Timex Sinclair
BASIC command set. Although the
instruction cards are concise, they
offer no one-location summary of all
the USR commands.
These two tapes can give you the
memory conservation and quickness
of machine code routines without the
aggravation of learning to program
yourself or the drudgery of POKEing
in someone else’s machine code. I
really enjoyed the “magic” I could
call up with a few keystrokes.
SINCLAIR /c^kT,ME t,mzex8%1o
I/O Board with our Real Time Clock /calendar
Time _ Month _ Date _ Year _ Day ot Week
23:59:59 12 31 99 7
Features
• 8 Outputs capable of driving relays
• 8 TTL inputs
• Feed through Sinclair Bus connector to
allow normal expansion
• Battery back-up for clock
• Expandable Ports
• All software included
• 90 day warranty
Future Products
• Touch Tone'“ encoder/decoder
• Speech and Sound synthesizer
MODEL
DESCRIPTION
PRICE
Built &
Tested
Bare PCB
& Manual
310
315
MASTER I/O WITH CLOCK
$59.95
$24.95
MODEL 310 ACCESSORY BOARDS
320
330
340
325
A to D and D to A converter
Wireless control system (BSR’“)
Solid State AC Relay
$47.95
$19.95
$69.95
$19.95
SPE
CIALIZED PARTS FOR MODEL 315
316
317
Sinclair edge connector, 46 pin w/key $12.95
Clock 1C and crystal (tested) $ 4.95
California residents add 6% Shipping and handling $ 3.95
Send self addressed
stamped envelope VVB
for catalog. P.O. Box 3295
Escondido. CA.92025-0580
VISA/MASTERCARD (619) 741-5132 (24 Hr Order Line)
Go FORTH
Name: ZXFORTH
Type: Language
ROM/RAM required: 8K/16K
Written in: Machine Code
Listable? No
Easy to load? Moderately
Printed listing? No
Documentation: Poor
By: International Publishing &
Software Inc.
From: Gladstone Electronics
1585 Kenmore Ave.
Buffalo, NY 14217
716/874-5510
or 1736 Avenue Road
Toronto, Ontario
Canada M5M 3Y7
416/787-1448
Price: $29.95
ZXFORTH ads boast the “simpli¬
city of BASIC with the speed of
machine code.” Although I can see
some uses for ZXFORTH, simplicity
is not among its virtues.
This operating system/language
comes on cassette with a 56-page
manual and a 5-page editor manual.
Instructions for loading both ZX¬
FORTH and the EDITOR appear on
the inside front cover of the FORTH
manual. This is about the only
tutorial material presented in either
book. They are reference manuals,
and as such will probably prove too
obscure for those with no knowledge
of FORTH.
VOTEM Lets Your
Computer See/$|fe\
The World W;
Analog Interface/Tape Signal Conditioner
(Tor the Timex/Sinclair Computer)
VOTEM is a complete package consisting of hard¬
ware and software that enables your computer to
measure, display and record "real world'' analog sig¬
nals. Your computer can monitor any physical phen¬
omenon (pressure, light, temperature, etc.) repre¬
sented by a DC voltage. A probe is provided for air and
liquid temperature measurements.
Your computer becomes a "smart' digital voltmeter
and thermometer with storage capability. Use VOTEM
in a home energy conservation project to save money
and possibly qualify for an energy tax credit.
VOTEM also cleans up the tape signal for reliable
LOADS. With VOTEM you can LOAD tapes with a
lower volume setting on your tape recorder.
VOTEM requires no mods, does not use the com¬
puter's rear expansion connector and works with 1 K
RAM (or more).
VOTEM is low priced at only $59.95 (assembled
and tested). For an even better bargain the VOTEM kit
is only $39.95. (Requires soldering and appx 2 hrs.)
VOTEM comes with a detailed 35-page manual. The
manual may be purchased separately for $5 pp and
applied to first purchase of a VOTE M unit. If you are not
satisfied with VOTEM return within 1 5 days for full
refund. (Does not apply to kits). Send check or money
order plus $3 for shipping and handling.
Down East Computers
P.O. Box 3096/Greenville, N.C. 27834
Experienced FORTH users may
have no trouble adjusting to ZX¬
FORTH, but most likely will consider
the implementation insufficient. The
editor uses line-by-line (not screen-
oriented) techniques; the badly
organized manual is written for the
wrong computer in parts (containing
many references to ASCII characters
not appearing on ZX/TS) and gives
examples that do not work.
I always find it difficult to work with
any language stored in RAM on a
typically ROM-based system,
because every time the computer
crashes I must reload the entire
language in addition to my pro¬
grams. This shouldn’t pose a prob¬
lem for a nice solid interpreter (how
often does BASIC crash?), but ZX¬
FORTH doesn’t fit the bill.
To anyone unfamiliar with
FORTH, this package bewilders.
Suddenly you must understand com¬
plicated stack operations, strange ter¬
minology and, worst yet, many
technical inaccuracies. On the other
hand, if you already know FORTH
or really want to learn it on your
ZX/TS, ZXFORTH will probably
work for you. The power is there if
you can figure out how to use it.
ZXFORTH works. Because of the
interpretation techniques, it is flexible
and fast. But if you expect to learn
FORTH, look elsewhere for your
text. These manuals will not lead you
by the hand.
for
TIMEX/SINCLAIR
computers
LOSTIN SPACE (uses SLOW) . 11.95
UNIVERSAL INVENTORY FILE . 16.95
UNIVERSAL MAILING LIST . 10.95
UNIVERSAL COIN COLLECTION . 10.95
UNIVERSAL STAMP COLLECTION . 10.95
UNIVERSAL COMIC BOOK COLL . 10.95
UNIVERSAL BASEBALL CARD COLL . . . 10.95
UNIVERSAL RECORD ALBUM COLL . . . 10.95
Each program on cassette +
manual. (8K ROM, 16K RAM)
Please add $1.50 for shipping and
handling. N.J. residents add 5%
tax.
M.C. HOFFMAN CO.
P.O. BOX 117
OAKLAND, N.J. 07436
56
SYNTAX QUARTERLY/SPRING 1983
HARDWARE REVIEW
The Parallel Connection
Product: Memotech Parallel Inter¬
face and Seikosha GP100A
Printer
From: Memotech Corp.
7550 W. Yale Ave. Suite 200
Denver, CO 80227
303/986-1516
Price: $408.95 for I/F, cable and
printer, including shipping
After my large box from Memo¬
tech arrived, I examined the com¬
ponents: a Memotech I/F, cable and
80-column printer.
I/F stands for interface, computer
jargon for the connection between
your ZX81 or Timex Sinclair 1000
and the printer. Memotech’s interface
is Centronics parallel-equivalent. So
any printer that uses a parallel printer
port (one of two common standard
ports) will work with it. This interface
uses decimal addresses 10500 to
11500. With a 64K RAM pack you
must only turn off the 8-12K area
because the addressing is fully de¬
coded. As with all Memotech prod¬
ucts, the I/F sandwiches with other
Memotech products (the I/F must
plug into the computer before
anything else). The product pack¬
aging is Memotech’s standard black
anodized case. The interface is FCC-
approved for RF noise.
Then I unwrapped the cable. It’s
made by 3M and has 34 pins on one
end, 36 pins on the other. The
36-pin end goes to the printer.
Finally, the printer emerged. It is
the same as Radio Shack’s Line
Printer 7, which sells for $399. It is
pin-feed only and prints about 30 cps
(characters per second), giving 80
columns in a 5x7 dot matrix. The
printer runs a little noisy, even with
the sound baffle on. You can get all
the paper or ribbons you need at
Radio Shacks anywhere.
Once I connected everything I was
able to print in minutes. The I/F uses
all the keyboard’s printer com¬
mands— no USR calls here. All
ASCII control codes are preceded by
an inverse period. Or you can use
the CFIR$ of the Sinclair code cor¬
responding to that character. Lower
case characters are represented by
inverse graphics. For example, in¬
verse B prints as “b”.
I have used my printer for a month
or so with no problems. The entire
package costs $408.95 and offers a
96-character ASCII character set
with lower case, double-wide charac¬
ters, and dot-addressable graphics.
In addition, it can print Memotech’s
hi-res screen. You get 80-column
printouts for LLIST and LPRINT;
COPY gives you exact screen image.
For the price, you can’t beat it.
Having gained considerable prac¬
tice with this unit, I will now pass on
my experience to you:
1. Memotech’s literature does not
go into detail about ASCII control
codes. Check at computer stores to
locate a good, detailed code guide.
Be sure to check all codes against
your printer’s guide because some
codes differ. For example, with the
Seikosha printer change the follow¬
ing: inverse period 8 — graphics
mode; inverse period A— NEWLINE
or ENTER; inverse period G — POS.
10 RFH
IS LET 8 = 16514.
20 INPUT R
30 POKE B R
4-0 XF i-j -t? THEN GOTO ISO
50 LET B=B+1
50 GOTO 20
100 LPRINT CHS $ 6
Program 1
SYNTAX QUARTERLY/SPRING 1983
57
BYTE-BACK modules
64- K MEMORY $119.??
INSTANT INFORMATION
WITH
BYTE-BACK’S MD-1
MODEM only $119 ■ KIT
WIRED AND TESTED $149.95
Use your phone to connect your “LITTLE” computer to
the “LARGEST” computer networks in the world, With
BYTE-BACK’s MD-1 MODEM connected all you do is dial
a phone number (usually local), press a few keys and watch
the data appear on your TV screen. (Software is included)
This MODEM can be used in either the “originate” or
“answer” mode with selectable baud rate.
You can have immediate access to:
UNIVERSITY COMPUTERS.DOW JONES.
COMPUSERVE & SOURCE
As an extra bonus an RS-232 port is provided to
allow you to drive all standard RS-232 peripherals &
printers. (75 to 9600 Baud)
BYTE-BACK’S BB-1
CONTROL MODULE
$59.00 in stock!
WIRED and TESTED $69
• 8 Independent Relays
(with LED status indicators)
• 8 Independent TTL Inputs
(with Schmitt trigger buffers)
• By using a single POKE command
you can change and latch the status
of each of the 8 relays.
• Your computer can read the status
of all 8 inputs by the use of single
Peek command.
• A comprehensive manual is in¬
cluded that has complete application
_ details.
WIRED and TESTED $129.95
INSTOCK!
SAME DA Y SHIPMENT!
WHY PAY MORE?
BYTE-BACK’S M-64 extends the memory of your ZX81 or
Timex-Sinclair 1000 to a full 64-K. It’s user transparent. It
plugs directly into the back of the ZX81 and has an
expansion port to allow you to still use a printer. No extra
power supply is required.
All Memories have extra tight contacts in the connector.
This combined with a flat-bottom metal case, provide the
shielding and stability needed to completely eliminate
memory “crashes” common with other memory modules.
EXPAND YOUR 16K SYSTEM
(M-16) $59,95
WIRED and TESTED $69.95
If you have a Sinclair 16K
RAM module and need more
memory, expand it to 32K and
beyond by using BYTE-BACK
M-16 MEMORY MODULES.
You can’t connect two Sin¬
clair 16K RAM modules together, but you can connect
one Sinclair 16K and one or more BYTE-BACK 16K
modules to get all the memory you need.
THOUSANDS IN USE WITH PROVEN RELIABILITY
IN STOCK — SAME DAY SHIPMENT
Don’t settle for a poor quality printer . . .
RS-232 Module $59.?!?
WIRED AND TESTED $69.95
Allows you to connect to all RS-232 printers & terminals.
ALL MODULES CARRY 90-DAY WARRANTY
Schematic & Manual included with all bd.s and urtits.
TRY BYTE-BACK MODULES FOR 10 DAYS WITH NO OBLIGATION
UJ h-
. “ O CM
O Q o> i-
OO" ®
X J9(M
wSk £
^ z < z
S 5 D
O UJ i -
w > z 08
II O h J
■ H o c o
; D . § O
a. c/> 2 i
:U
i O uj to
Remember with: BYTE-BACK modules you are NOT limited to using only one module at a time!
h- x > ^
O C/> JZ
m CD UJ q.
0- Z < gQ
o w -
0CDCQS
UJ . UJ
(5 — 1 to i
^ D UJ o
m Q o d
w ° z iu ,
h 2 uj □ I
> a _l ;
CD ofi < < l
□ M-64 Kit . $119.95
□ M-64 Wired and Tested . $129.95
□ M-64 Blank PC Board . $19.95
□ BB-1 . $59
□ BB-1 Wired . $69
□ BB-1 Blank PC Board . $19.95
ORDER PHONE (803) 532-5812 Bill My
□ M-16 Kit . $59.95
□ M-16 Wired and Tested . $69.95
□ M-16 Blank PC Board . $19.95
□ iModem Kit . $119.95
□ IModem Wired and Tested . $149.95
□ IRS-232 Module Kit . $59.95
□ RS-232 Module Wired and Tested . $69.95
Shipping and Handling $4.95
□ Visa □ MasterCard
Exp. Date _ Card No. _
Name _
Address _
City/State/Zip _ : _
Mail To: BYTE-BACK CO.* RT. 3 BOX 147 • BRODIE RD. • LEESVILLE, S.C. 29070
DEALER DISCOUNT AVAILABLE
CHECKS
■■l/OC'N]
fC4 MosteCard
58
SYNTAX QUARTERLY/SPRING 1983
£HjfM HARDWARE review
2. When using LPRINT and TAB
you can only TAB 32 positions. To
use the printer’s full width, substitute
LPRINT “inverse period Gxx”;
“Data” where xx is 0 to 80. This
prints at character position xx.
3. Instructions from Memotech do
not directly tell you how to use the
printer’s dot-addressable graphics
feature. But one part shows how to
POKE codes into a REM statement
and print symbols for these values.
That’s how.
To demonstrate, key in program
1. Line 10 contains 50 repetitions of
the letter A (any character would
do). Line 15 starts at the first
memory address after the REM in
line 10. A in line 20 is the decimal
Product: Floppy Interface for ZX81
(FIZ)
From: Macronics Systems Ltd.
26 Spiers Close
Knowle, Solihull
West Midlands, UK B93 9ES
Price: $149 for card only, $35 for ex¬
pansion bus. Shipped airmail
at no extra charge.
Macronics’ is the first disk drive
interface that appeared for testing
with ZX81 computers. The interface
card (5x5V2 inches) fits onto a
motherboard so you can use a
printer and external RAM pack. Any
RAM pack that lets you switch off the
8-12K region of RAM will work with
this system.
You can supply your own disk
drive or get one from Macronics.
Theirs is a standard 5V4 inch floppy
drive. (According to Ken MacDonald
of Macronics, their 3-inch drives
should be available around March,
1983. In the US, a Shugart SA400
or equivalent can work with this
interface — Ed.) A 21-inch cable
couples the drive to the interface
card. This cable is more than ample
to move the disk unit into an easy
working position.
number you will enter. Line 30 puts
each decimal number in a memory
location. Line 40 checks for a zero
input (0 tells the subroutine to exit
and print).
Now RUN the program. Enter
each decimal number following (hit
NEWLINE or ENTER after each):
8 (puts printer in graphics mode)
27 (ESCape, when followed by
POS specifies dot-address)
16 (POSition)
1 (High Point)
100 (Low Point)
2, 255, 186, 160, 178, 191, 178,
160, 178, 191, 178, 160, 186,
255, 2 (graphics data— see
manual)
0 (tells subroutine to exit and
print) .
Fiz-zy Floppy
You switch on the disk drive
before applying power to the com¬
puter. Here I ran into my first prob¬
lem— there is no way to tell that
everything is alright. Usually, a disk
system’s software first tests the drive
so you hear the motor when you
switch on the power. Not so on the
Macronics drive. You might expect
to see the LED on the front light
when the power comes on. Not so.
This LED only comes on when the
computer uses the drive. In fact, this
software only responds to USR calls;
otherwise it is inactive.
To use this system, you need
single-sided, single-density, hard
sectored disks. These disks are di¬
vided into 10 sectors. Because each
disk contains 35 or 40 tracks, you get
350 or 400 segments of data, but
each file must use a whole number of
tracks. With 35-track disks, you get
42. 5K bytes maximum storage;
48.75K with 40-track disks. Each
data segment is 128 bytes long. The
whole first track is used for the direc¬
tory. This leaves you with no more
than 48K on each disk and no more
than 39 files per disk. Of course, you
can swap disks during a program for
greater storage capacity.
High Point (HP) and Low Point (LP)
combined form a 4-byte dot address
that can range from 0 to 479 decimal
or 01DF hex (the dot-address of the
last character). Here is the snag. HP
must equal either 00 hex (if the ad¬
dress is less than 256) or 01 hex (if
the address is greater than or equal
to 256). Yet if you enter 00, the
subroutine exits and you get no print.
The printer only checks whether bit 7
of the HP is on or off. Instead of 00
hex, enter 16 decimal. For 01 hex
enter 01 decimal. LP can be any
number between 0 and 255 decimal,
or 00 and FF hex.
Jeff Pack
Auburn, WA
Disk systems’ speed usually at¬
tracts people, but this one is SLOW
compared to most. Software entirely
controls the disk— there is no con¬
troller board.
This system takes 24 seconds to
load a 16K program from disk into
memory. (MacDonald says it takes
18 seconds — Ed.) Although this
speed is 21 times the speed of
cassette loading, it is six times slower
than Sinclair’s forecast ZX Spectrum
Microdrive and 60 times slower than
normal disk drives for other
computers.
Despite the slow speed, Mac-
ronic’s disk system is ideal for ZX/TS
users. It is simple to operate and
understand.
Technical Details
Files always use a whole number
of tracks and your program must dis¬
cern what data is in each sector of the
file. The disk system provides 10
commands that you can use in pro¬
grams via one USR call to Macronic’s
4K ROM on the interface board. This
command, LET E = USR 9999,
should be the first line of any pro¬
gram. All other commands are then
SYNTAX QUARTERLY/SPRING 1983
59
ij^lcTH ARP WARE REVIEW
available as USR calls to the ROM
using letters or words instead of
numbers. For instance, USR DIR
calls the directory (2-second access
time), which prints disk contents on
the screen by file name only. DIR has
no effect on your program except to
clear the screen. You can COPY the
directory listing.
Each file name consists of six let¬
ters, no spaces, followed by a full
stop (period). Then comes a three-
letter description of the file type
(DAT for data, BAS for BASIC, for
example). You can invent your own
codes if you like.
To create data files, you must first
give variable F$ the name of the file
in the format just described. Then
assign the number of sectors required
(in multiples of 10) to variable R. The
command LET E = USR CREATE
will then make a new file. If a file of
the same name exists, the system will
not overwrite it, but return the
variable E with an error code. You
can only copy a file by giving it
another name and only destroy it by
a KILL command.
READ and WRITE use variable
R$, which has been dimensioned to
be 1x128 bytes long to read and
write sectors into and out of
memory. You use R for the number
of sectors required and F$ for the file
name. R may not be a FOR-NEXT
loop variable.
ST AT gives the disk status. If
F$ = “” (no file name), ST AT gives
the number of free sectors on the
disk. If F$ contains a file name,
ST AT returns the number of sectors
that file uses.
DSAVE and DLOAD do the same
as on the cassette, so you can LOAD
files into the computer from tape and
DSAVE them onto disk. You can
also make programs auto-run.
NEWD initializes a new disk, filling
every sector with check characters
and writing out the directory track.
The supplied interface card has 2K
RAM for use as work space for the
disk at 14-16K. It also contains a 4K
ROM using addresses 8-12K. (Ac¬
cording to Ken MacDonald, the FIZ
uses 240 bytes of ZX/TS RAM in the
variables region — Ed.)
Conclusions
This disk system in no way rivals
Sinclair’s Spectrum Microdrive
(when available) . Sinclair’s Micro¬
drive will not work with ZX81s or
TSIOOOs and will beat Macronics’
drive both in capacity (100K per
disk, eight drives) and price (about
£50, or $82 US).
However, the ZX81 (and TS1000)
is well used all over the world and the
Spectrum has been only available in
the UK. ZX/TS users who do not
want to change their machine and
software will find this a very useful,
but expensive way to speed up data
processing.
Keyboard
Product: Auto Shift Keyboard Kit for
ZX/TS
From: Research Applications
Products
4561 Paloma Lane
Yorba Linda, CA 92686
Price: Kit $80
Board and Key Legends $30
I picked up my keyboard kit at
Research Applications, so I did not
have to wait for mail order delivery.
Although you can buy the PC
(printed circuit) board and key
legends for $30, I opted for the com¬
plete kit. Compared to rounding up
the remaining components, the
savings didn’t seem worth the hassle.
One double-sided PC board, 73
keys and key caps, 7 CMOS ICs and
sockets, 27 resistors, 27 diodes and
mylar key legends make up the kit. It
does not come with an enclosure,
but this was no problem — it fits easily
into a surplus enclosure I bought
locally for $6.
Construction time was about four
hours— there are 134 components
and 73 separate key legends to
mount.
Keyboard connection to the com¬
puter is via ribbon cable which you
There are a few things I’d like to
see Macronics change:
1. An at-a-glance list of commands
would be better than leaving the
commands spread throughout the
manual.
2. A POWER ON indicator would
be useful on the disk drive.
3. Arrangements should be made to
have 48K RAM packs available for
use with the system.
4. Use DIM R$(l,128) instead of
DIM R$(128). This would allow users
to INPUT directly to the variable used
by the disk and save memory.
Stephen Adams
London, England
Quickness
solder to the board at one end. You
then strip and tin the connectors on
the other end before inserting them
into existing sockets on the com¬
puter. (The connectors are on 0.1
inch centers and slip directly into the
sockets.)
For ease of use, I replaced the kit’s
ribbon connector with a five-foot
length, which resulted in the autoshift
LPRINT not working. Fortunately,
the instructions addressed this prob¬
lem. 1 easily solved it by adding a
6.8K resistor in parallel with the 10K
pull-up resistor on the computer
KBD0 line.
My completed keyboard is profes¬
sional in appearance and extremely
easy to use. As advertised, 46 key
functions are automatically shifted.
The keyboard layout is logically ar¬
ranged with a special graphics sec¬
tion. The editing/game keyrow
(located at the bottom of the key¬
board) is a nice touch. This feature
gives you quick and easy program
editing with single keystrokes and
contains the cursor arrows used in
many games.
Don Parks
Riverside, CA
60
SYNTAX QUARTERLY/SPRING 1983
IMcHbook review
Pocket
Information
Title: The ZX81 Pocket Book
Author: Trevor Toms
From: Reston Publishing Co., Inc.
599 Adamsdale Road
N. Attleboro, MA 02760
Price: $10.95
For a 128-page paperback, $11 is
a lot of money to pay. But Trevor
Toms has done a good job here.
There are a couple dozen programs
and subroutines, mostly games but
also a few handy utilities: big char¬
acters, a hex monitor, and a couple
of very nice routines for formatted
numeric output are included. All the
programs I tried were good to
excellent.
There is also a good deal of text
aimed at the moderately experienced
user who wants to develop tech¬
niques for running faster programs
and using less memory, and methods
and algorithms for doing things that
aren’t completely straightforward in
Sinclair BASIC. Anyone past the
beginner level will find some useful
ideas in this book. For instance,
which is better: A = B*0.15 or
A = B * 100/ 15? Toms points out that
while the first is faster, it turns out to
be less accurate; INT (100*0.15)
returns a value of 14!
Minor errors mar the book. Toms
originally wrote the book for an
English audience, and this American
edition lacks some necessary correc¬
tions. For example, the statement
that FRAMES is updated at intervals
of 1/50 of a second was not changed,
though in the American ZX/TS com¬
puters it’s 1/60 second. In addition,
in the section on reducing execution
times, some benchmark programs
are listed and it says that there is a
table of timings at the end of the
book. There is not. Remarkably, I
found no bug or typo worth mention¬
ing in any of the programs— even the
long and complicated . “Adventure
Master” given in the last chapter.
This marvelous program is, in ef¬
fect, an interpreter for a language to
create adventure-type games. Toms
gives two sample scenarios, a tiny
test scenario and a more complex
one, “City of Alzan.” The latter is
fairly simple but fun, and it doesn’t
begin to strain even a mere 16K
RAM’s capacity. If you’d like to make
your own clever and complicated
adventure game, this program
should give you all the tools you’ll
need. This chance to create your
own adventure game may justify the
price of the book.
Richard S. Holmes,
Batavia, IL
Know Your CPU
Title: Z80 User's Manual
Author: Joseph J. Carr
From: Reston Publishing Co.
A Prentice-Hall Co.
Reston, VA
Price: $10.95 (326 pp., softcover)
In a nutshell, the Z80 Users Man¬
ual is an excellent reference but not
an instruction manual for beginners.
While most Z80 hardware techni¬
cal manuals tell you what you need
to know about any given facet of the
computer’s operation in five different
places, Carr’s Z80 Users Manual tells
you everything you need to know in
one place. For instance, in the
description of the memory refresh
register R, this manual tells not only
what the R register does, but that the
I register is placed on the high order
bits of the address bus, and R register
on the low order bits, and that the R
register does not increment through
the eight bit— all important informa¬
tion when trying to understand
ZX/TS character generation and
keyboard scanning. This sort of infor¬
mation may be split up in other man¬
uals, or may not be presented at all. I
wish this book had been around
when I learned Z80 architecture and
programming!
To understand the hardware sec¬
tion, you should have some familiar¬
ity with digital logic, since it is used
extensively.
The hardware section includes in¬
terfaces for RS232 and current loop
devices, I/O port interfacing, mem¬
ory mapping, a good description of
interrupts, explanation of ASCII and
EBCDIC codes (neither of which the
ZX81 uses), and short descriptions of
the Z8 and Z8000 microprocessors,
which will give you a more worldly
view of microprocessors.
The software section of the manual
describes how addressing modes
work, interrupts from a software
standpoint, and, to some degree,
coding techniques. In the software
portion of the book, Carr assumes
you understand logical operators
(AND, OR, etc.); he gives no expla¬
nations while using the terms.
The last chapter is a comprehen¬
sive description of the Z80 instruction
set, similar to those published in any
book on Z80 microprocessors, al¬
though a little better done than most.
This book is not for beginners with
no experience or concept of how
machine code works. It may also be
over the heads of those just beginning
in digital circuitry. It is a very good
reference work for those who are
eager to learn.
Carr presents concepts in a clear,
concise form, including everything
you need to know on a subject in one
place. This manual does not tell you
amazing things people didn’t know
before; it retells the old story in an
understandable form. A warning,
however: this book does not deal
specifically with the ZX81 at all, and
most of the circuits given will require
some modification. In general, the
circuits are shown as concepts, and
therefore will not work as is.
SYNTAX QUARTERLY/SPRING 1983
61
SYNTAX
Serving Timex-Sinclair
Personal Computers
A PUBLICATION OF THE HARVARD GROUP
ISSN 0273-2696
SYNTAX is a monthly newsletter exclusively for ZX80/
81/TS1000 owners. We bring you news, reviews and ap¬
plications for your computer, plus technical notes for
circuit-builders. SYNTAX also provides a forum for
thousands of users to share advice and problems about
programs and vendors. We bring you timely updates
about new hardware, software and books. And we cover
all the Sinclair-technology computers, including the new
TS1000.
At SYNTAX we emphasize practicality. You can apply
our suggestions even if you aren’t sure at first why they
work, because we give you complete instructions. Text is
clear and easy to understand. SYNTAX readers already
know about:
• An automatic phone-dialer they can put together
in a few hours
• Syntactic Sums™ to check input for errors
• Programs to explore computer memory
• How to build external additional RAM
• How to add an 8212 I/O chip to control external
devices from their computers
And SYNTAX readers like what they get every month.
Subscribers know they can depend on us.
After receiving only three issues of SYNTAX , I
find that I anxiously await the next. . . keep up
the good work!
Martin Irons
Goshen, NY
Congratulations on the brass-tacks, down-to-
earth approach of your newsletter. Til be look¬
ing forward to future issues.
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Washington, DC
Many readers get their first issue and immediately order
the back issues— more proof that they like what they see.
You can see what’s special about our publication. We
work hard to bring you a quality newsletter. We strive to
print useful programs of above-average accuracy. As any
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curacy is tough to achieve, but we boost our average with
every issue. We test each program to make sure it works,
it fits in the designated RAM, and it runs when you follow
the directions. We print program listings in screen-image
format to make it easier for you (it’s sure not easier for
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Sum™ as an additional aid for you in getting error-free
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thousands of other readers, and our staff experts are
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solve problems with your machine.
SYNTAX readers get every month:
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• Do-it-yourself additions
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To share the benefits of SYNTAX, just indicate your
choices on the order coupon and return it with your
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We are so sure you’ll find SYNTAX useful that we
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Join the others who stretch the ZX/TS to the utmost.
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phone your credit card order to 617/456-3661. Don’t
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Fill out the coupon below and mail it to: SYNTAX/SQ, RD2 Box 457, Harvard, MA 01451
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These offers expire 31 May 83-SUBSCRIBE NOW.
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62
SYNTAX QUARTERLY/SPRING 1983
(^fral SYNTAX QUARTERLY
^~=> JL^J> by The Harvard Group
Increase Your
Computer’s Utility
With Our Help
You own a powerful computer, capable of sorting,
analyzing, calculating, displaying and manipulating
data as well as measuring and controlling. Despite its
small size, your computer will help you learn, analyze
your business, keep your records or your schedule, dial
your phone, send messages, or talk to other computers.
To control the power available to you, you’ll need hard¬
ware and software to use with your machine. Although
you can buy many of these products— and we’ll tell you
about them— some you must create or modify for your¬
self. SQ will provide you with the complete information
to let you use your programming or tinkering time
efficiently.
Our experts also bring you SYNTAX, the newsletter,
for up-to-date, concise information. You need news and
new product announcements quickly. And SYNTAX
packs a lot of information into its brief, time-saving
format.
But we recognized your need for material too long to fit
in SYNTAX. Syntax Quarterly fulfills that special need.
In-depth, extensive, detailed information— that’s what
SQ’s all about. Long programs, big construction articles,
and detailed directions help you use your computer to its
fullest while learning.
SQ gives you tested, accurate information that you can
depend on. We test, we build, we check everything that
goes into SQ. Our staff experts work for you; it’s as
though your full-time staff prepared a report for you
every quarter.
At SQ, we specialize in your machine— Timex-Sinclair
technology. Our programs and projects work, and,
because we test each one before we publish it, they work
on your machine. All the information in SQ can work for
you.
But, to capture these benefits— free software, free
plans for hardware, free instruction — you must subscribe.
Use the coupon to tell us how to help you best. Or call;
we understand people in a hurry. SQ
1
100 LET R* = ’
200 LET B$="
250 LET C$="_
300 PRINT
4-00 PRINT B$].B$
500 PRINT B$( TO 73 .6$
600 PRINT Bit TO 73 jet
70© PRINT fii,B$
600 PRINT " " ; B $ 1 2 TO ) ,Bt
y00 PRINT ** TO } 'b*
1000 PRINT B$,B£
1100 PRINT
1200 PRINT RT 7,22; C*
1300 PRINT RT 9,24.: C*
14-00 FOR 1=0 TO 24-8
I >66 RND I <126 THEN GOTO
1600
1500 PRINT CHRi I;
16©0 NEXT I
170© PRINT RT 1© ,8;" UE SPERK V
OUR LRNGURGE
SYNTRCTIC SUM: 22174- , BK ROM
UE SPERK YOUR LRNGURGE 0123
— — - J"RT TRB 7CODE URL LEN
SIN COS TRN RSN RCS RTN LN EXP
intsor SGN RBS PEEK USR STR* CH
R* NOT ** OR RND <=>=<> THEN TO
STEP LPRINT LLIST STOP SLOU FRST
NEU SCROLL CONT DIM REM FOR GOT
O GOSUB INPUT LORD LIST LET PRUS
E NEXT POKE PRINT PLOT RUN SWE
617/456-3661
SYNTAX QUARTERLY/SPRING 1983
617/456-3661
63
li^jg i BOOK REVIEW
Inside Story
t z-
^ Ft
f 6V*
t-
Title: Secret Guide to Computers
Author: Russ Walter
From: Secret Guide to Computers
Company
92 Saint Botolph St.,
Boston, MA 02116
617/266-8128
Price: $3. 70/each or 8 vol. set for
$29.60
The tenth edition of Russ Walter’s
Secret Guide to Computers is prob¬
ably the funniest, most interesting,
most entertaining computer learning
guide ever written; however, it con¬
tains little on the ZX/TS computers.
Learn the ZX’s BASIC first, then buy
the guides.
Here’s a rundown of all eight vol¬
umes of the Secret Guide to Com¬
puters. Volume 1 starts the reader off
with a lesson on the keyboard then
proceeds to fixing mistakes, math,
variables, input, program storage,
logic, and all the other necessities so
you can get started with BASIC on
most micros, some minis, and some
maxis.
Deeper into BASIC
Volume 2 digs deeper into BASIC. It
includes information on ON . . .
GOTO and ON...GOSUB state¬
ments (something the ZXs don’t
have), error handling, error trapping,
simpleton graphics, advanced funda¬
mentals, programming style, math
functions, sorting, and text files. This
volume is the most helpful for ZX
users since neither the ZX80 nor the
ZX81 manual mention anything
about graphics, fundamentals, or
style and sorting.
Volume 3 covers hardware, buying
a computer, computer companies,
peripherals, explanation of the Cen¬
tral Processing Unit (CPU) , and a run¬
down of the major microcomputers.
The Computer Field and
Basic Applications
Volume 4 digs deep into the com¬
puter field. It rehashes the major
microcomputer manufacturers, and
goes over the major points of buying
a big computer. This volume also
covers the different number systems,
getting a job in the computer field,
what to read, and computer courses
offered by the author.
Volume 5 covers some basic appli¬
cations. For example: games, exten¬
sive graphics, and the all-important
VISICALC and its mates SUPER¬
CALC, SPECTACULATOR, and
word processing in most micros.
Volume 6 isn’t available but I con¬
tacted the author who said it will
cover artificial intelligence and ex¬
pand on Volume 5.
Volume 7 covers FORTRAN,
PASCAL, COBOL and Volume 8
goes into an extensive overview of all
the computer languages but doesn’t
teach you how to use them. Volume
8 also goes into the history of the
CPU and how to program in assem¬
bly language for most of the CPUs.
Yet, I suggest buying Dr. Ian Logan’s
book written especially for the ZXs
because Volume 8 doesn’t tell you
how to go about assembling. It just
explains various mnemonics.
Overall, Russ Walter’s eight-
volume guide is both fun and very in¬
formative. Most computer books are
too technical, but the Secret Guide is
written in plain English.
Peter Nichols, Hanover, MA
Ad Index
Brainchild Computer Works 52
Byte- Back Co. 58
Compuwiz Software 36
Dallas Development 21
Down East Computers 56
E-Z Key 37
Ezra Group II 36
Frog Software 64
General Systems Consulting 23
Gladstone Electronics 13
M.C. Hoffman 56
Innovation Company C3
Intercomputer, Inc. 17
International Publishing & Software 1
JK Audio 56
Kopak Creations, Inc. C4
Melbourne House Software 33
Memotech Corporation 7
Mindware, Inc. C2
Sinware 6
Softsync, Inc. 18
Syntax/SQ 3, 16, 62, 63
Tom Woods 64
Z-Ware 64
Z-Ware Sale
ZX81 /TS-1 000 Software on
Cassette
$8.95 each ppd.
1 6K Histogram — plots bar chart
1 6K Financial Manager— for
home or business
16K Machine Intelligence
Demo — life forms that actually
learn.
Many more available — send
self-addressed, stamped en¬
velope.
Z-Ware
Box 111
Albany, Kentucky 42602
1-606-387-8391
LEARN TO
PROGRAM
Text and File Organizers with
ZX DATA FINDER
A high capacity information
storage and retrieval tool for
16 K Timex and Sinclair Com¬
puters.
Advanced file input and editing
routines are thoroughly
analyzed.
Comprehensive search and
display methods are fully
explained.
AN ADVANCED COURSE
IN DATA HANDLING
Free specifications are
available, or send $9.95 for
program listing and text to:
THOMAS B. WOODS
P.O. Box 64, Jefferson, N.H. 03583
ARTIFICIAL INTELLIGENCE
FOR THE ZX81?
YES!
SYNCZX is an artificial intelligence
program with natural language capabili¬
ties for the ZX81 with 16K RAM, avail¬
able from Frog Software.
SYNCZX will talk to you in ENGLISH/
NO MENUS. You can use SYNCZX to
balance your checkbook or you can
reprogram SYNCZX to do anything you
would like. However you do not need pro¬
gramming skills to use SYNCZX as is.
Even a child can use SYNCZX because it
is easy to read and understand, talking
to you in simple English. SYNCZX even
remembers the people who use it! 16K
cassette with manual only $6.95 plus
$1.50 postage & handling.
Frog Software
Box 95
Glenmont, New York 12077
(518) 465-6552
64
SYNTAX QUARTERLY/SPRING 1983
Live Music
Archive
Librivox
Free Audio
Metropolitan Museum
Cleveland
Museum of Art
Internet
Arcade
Console Living Room
Open Library
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Libraries
TV News
Understanding
9/11